SC TO-T/A

QuickLinks -- Click here to rapidly navigate through this document

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE TO
(Rule 14d-100)

TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1)
OF THE SECURITIES EXCHANGE ACT OF 1934
(Amendment No. 23)

Alcan Inc.
(Name of Subject Company (Issuer))

Rio Tinto Canada Holding Inc.
an indirect wholly-owned subsidiary of Rio Tinto plc
and
Rio Tinto plc
(Names of Filing Persons (Offeror))

Common Shares
(Title of Class of Securities)

(013716105)
(CUSIP Number of Class of Securities)

Ben Mathews
Rio Tinto plc
6 St James's Square
London SW1Y 4LD
United Kingdom
Tel: 011 44 20 7930 2399
with a copy to
Thomas B. Shropshire, Jr.
Linklaters LLP
One Silk Street
London EC2Y 8HQ
United Kingdom
Tel: 011 44 20 7456 2000

(Name, Address and Telephone Number of Person Authorized
to Receive Notices and Communications on Behalf of Bidders)

CALCULATION OF FILING FEE:

Transaction Valuation(1)	Amount of Filing Fee(1)(2)
$19,065,207,127	$585,302

(1)

For purposes of calculating the filing fee pursuant to Rule 0-11(d) only, the transaction value of the Alcan Common Shares to be received by Rio Tinto, assuming acceptance of the Offer by holders in the United States, is calculated as follows: 188,764,427 Alcan Common Shares in the United States, representing 50% of the entire issued share capital, multiplied by $101, the cash consideration being offered per Alcan Common Share, which yields $19,065,207,127, multiplied by 0.0000307, which yields $585,302. Each of the capitalized terms used is defined below.

(2)

Sent via wire transfer to the SEC on July 24, 2007.

o

Check box if any part of the fee is offset as provided by Rule 0-11(a)(2) and identify the filing with which the offsetting fee was previously paid. Identify the previous filing by registration statement number, or the Form or Schedule and the date of its filing.

Amount Previously Paid	Filing Party:
Form or Registration No.:	Date Field:

o

Check the box if the filing relates solely to preliminary communications made before commencement of a tender offer.

Check the appropriate boxes below to designate any transactions to which the statement relates:

ý

third-party tender offer subject to Rule 14d-1.

o

issue tender offer subject to Rule 13e-4.

o

going-private transaction subject to Rule 13e-3.

o

amendment to Schedule 13D under Rule 13d-2.

Check the following box if the filing is a final amendment reporting the results of the tender offer: o

        This Amendment No. 23 further amends and supplements the Tender Offer Statement on Schedule TO originally filed with the Securities and Exchange Commission on July 24, 2007 (as amended, the "Schedule TO"), by Rio Tinto plc and by Rio Tinto Canada Holding Inc., an indirect wholly-owned subsidiary of Rio Tinto. Unless otherwise defined herein, all capitalized terms shall have the meaning given to them in the Circular filed as Exhibit (a)(1)(A) to the Schedule TO.

        On October 24, 2007, Rio Tinto issued a press release announcing changes to its Board of Directors. This press release has been filed as Exhibit (a)(5)(GG) hereto and is incorporated herein by this reference. Also, on October 24, 2007, Rio Tinto issued a press release announcing the commencement of the Subsequent Offering Period. This press release has been filed as Exhibit (a)(5)(HH) hereto and is incorporated herein by reference.

ITEM 4. TERMS OF THE TRANSACTION

        Item 4 of the Schedule TO is hereby amended and supplemented as follows:

        On October 23, 2007, all of the conditions to the Offer had been satisfied and the Initial Offering Period, which was extended until October 23, 2007, was closed for acceptance. The Offeror has taken up all the Alcan common shares validly deposited under the Offer and those shares may no longer be withdrawn. Settlement of the Offer will take place on October 25, 2007.

        Alcan shareholders who have not yet accepted the Offer may tender their Alcan common shares pursuant to a subsequent offering period commencing on October 24, 2007 and expiring at 6:00 p.m. Canadian Eastern time (11:00 p.m. London time) on November 8, 2007 for the same consideration and pursuant to the terms set out in the Circular. The Offeror will immediately take up and promptly pay for all Alcan common shares validly deposited under the Offer during the Subsequent Offering Period. The Offeror will permit withdrawal of Alcan common shares deposited during the Subsequent Offering Period, at any time prior to the expiration of such Subsequent Offering Period; provided, however, that this right of withdrawal will not apply in respect of Alcan common shares taken up by the Offeror prior to the Subsequent Offering Period. Withdrawing holders of Alcan common shares who have deposited such Alcan common shares during the Subsequent Offering Period and have received payment for such Alcan common shares must return such payment to the applicable Offeror prior to any withdrawal.

ITEM 12. EXHIBITS

(a)(1)(A)°	Circular, dated July 24, 2007.
(a)(1)(B)°	Form of Letter of Transmittal.
(a)(1)(C)°	Form of Notice of Guaranteed Delivery.
(a)(1)(D)°	Form of Letter to Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees.
(a)(1)(E)°	Form of Letter to Clients for use by Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees.
(a)(5)(A)°	Summary Advertisement in The Wall Street Journal, dated July 24, 2007.
(a)(5)(B)°	Press release announcing commencement of the Offer, dated July 24, 2007.
(a)(5)(C)°	Transcript of interview with Bloomberg UK, dated July 12, 2007.
(a)(5)(D)°	Transcript of interview with CNBC Europe, dated July 12, 2007.
(a)(5)(E)°	Transcript of interview with CNN International, dated July 12, 2007.
(a)(5)(F)°	Transcript of interview with CNBC US, dated July 19, 2007.
(a)(5)(G)°	Management slide presentation by Rio Tinto plc, dated August 2, 2007.
(a)(5)(H)°	Script of management slide presentation by Rio Tinto plc, dated August 2, 2007.
(a)(5)(I)°	News release announcing half-year results, dated August 2, 2007.
(a)(5)(J)°	Transcript of interview with BNN, dated July 18, 2007.
(a)(5)(K)°	Transcript of interview with the Australian Broadcasting Corporation, dated July 23, 2007.
(a)(5)(L)°	Memorandum to managers of Rio Tinto and Alcan, dated August 2, 2007.
(a)(5)(M)°	Press release relating to the Offer, dated August 7, 2007.
(a)(5)(N)°	Frequently Asked Questions about the Rio Tinto Offer for Alcan Inc., dated August 20, 2007.
(a)(5)(O)°	Press release announcing extraordinary general meetings, dated August 24, 2007.
(a)(5)(P)°	Press release announcing US antitrust approval, dated August 27, 2007.
(a)(5)(Q)°	Press release announcing completion of loan syndication for financing of Alcan acquisition, dated August 30, 2007.
(a)(5)(R)°	Press release announcing Canadian Competition Act clearance, dated August 30, 2007.
(a)(5)(S)°	Press release announcing Rio Tinto plc Extraordinary General Meeting, dated September 14, 2007.
(a)(5)(T)°	Notice of extension of the Offer, dated September 17, 2007.
(a)(5)(U)°	Letter to shareholders of Alcan announcing the extension of the Offer, dated September 17, 2007.
(a)(5)(V)°	Press release announcing the extension of the Offer, dated September 17, 2007.
(a)(5)(W)°	Press release announcing approval of the acquisition of Alcan by Rio Tinto shareholders, dated September 28, 2007.
(a)(5)(X)°	Press release announcing European competition clearance, dated October 2, 2007.
(a)(5)(Y)°	Press release announcing Australian Competition & Consumer Commission clearance, dated October 3, 2007.
(a)(5)(Z)°	Press release announcing French Government approval, dated October 4, 2007.
(a)(5)(AA)°	Press release announcing Exon-Florio clearance received, dated October 5, 2007.
(a)(5)(BB)°	Press release announcing Australian Foreign Investment Review Board approval, dated October 9, 2007.
(a)(5)(CC)°	Press release announcing Proposed Aluminium Business Executive Management Team, dated October 10, 2007.
(a)(5)(DD)°	Press release announcing receipt of Investment Canada Act approval, dated October 18, 2007.
(a)(5)(EE)°	Joint press release by Rio Tinto and Alcan, dated October 18, 2007, announcing receipt of regulatory approvals.
(a)(5)(FF)°	Advertisement dated October 19, 2007.
(a)(5)(GG)	Press release announcing changes to the Rio Tinto Board of Directors, dated October 24, 2007.
(a)(5)(HH)	Press release announcing the commencement of the Subsequent Offering Period, dated October 23, 2007.
(b)(1)°	Facility Agreement, dated July 12, 2007, among Rio Tinto, Credit Suisse, Deutsche Bank AG, London Branch, The Royal Bank of Scotland plc, and Societe Generale.
(d)(1)°	Support Agreement, dated July 12, 2007, among Alcan, the Offeror and Rio Tinto.
(d)(2)°	English language translation of undertakings and confirmations made by Rio Tinto and Offeror to the Government of Quebec and Alcan, dated July 11, 2007.
(d)(3)°	Confidentiality Agreement, dated April 11, 2007 between Alcan and Rio Tinto.
(d)(4)°	Amendment to Confidentiality Agreement, dated June 25, 2007.
(d)(5)°	Standstill Agreement, dated June 13, 2007, between Alcan and Rio Tinto.
(d)(6)°	Amendment to Support Agreement, dated July 20, 2007, among Alcan, the Offeror and Rio Tinto.
(g)°	None.
(h)°	None.

°

Previously filed with the SEC.

SIGNATURE

        After due inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Date:  October 24, 2007	RIO TINTO PLC
	By:	/s/  GUY ELLIOTT
	Name: Title:	Guy Elliott Finance Director
	RIO TINTO CANADA HOLDING INC.
	By:	/s/  IAN RATNAGE
	Name: Title:	Ian Ratnage Director

EXHIBIT INDEX

(a)(1)(A)°	Circular, dated July 24, 2007.
(a)(1)(B)°	Form of Letter of Transmittal.
(a)(1)(C)°	Form of Notice of Guaranteed Delivery.
(a)(1)(D)°	Form of Letter to Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees.
(a)(1)(E)°	Form of Letter to Clients for use by Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees.
(a)(5)(A)°	Summary Advertisement in The Wall Street Journal, dated July 24, 2007.
(a)(5)(B)°	Press release announcing commencement of the Offer, dated July 24, 2007.
(a)(5)(C)°	Transcript of interview with Bloomberg UK, dated July 12, 2007.
(a)(5)(D)°	Transcript of interview with CNBC Europe, dated July 12, 2007.
(a)(5)(E)°	Transcript of interview with CNN International, dated July 12, 2007.
(a)(5)(F)°	Transcript of interview with CNBC US, dated July 19, 2007.
(a)(5)(G)°	Management slide presentation by Rio Tinto plc, dated August 2, 2007.
(a)(5)(H)°	Script of management slide presentation by Rio Tinto plc, dated August 2, 2007.
(a)(5)(I)°	News release announcing half-year results, dated August 2, 2007.
(a)(5)(J)°	Transcript of interview with BNN, dated July 18, 2007.
(a)(5)(K)°	Transcript of interview with the Australian Broadcasting Corporation, dated July 23, 2007.
(a)(5)(L)°	Memorandum to managers of Rio Tinto and Alcan, dated August 2, 2007.
(a)(5)(M)°	Press release relating to the Offer, dated August 7, 2007.
(a)(5)(N)°	Frequently Asked Questions about the Rio Tinto Offer for Alcan Inc., dated August 20, 2007.
(a)(5)(O)°	Press release announcing extraordinary general meetings, dated August 24, 2007.
(a)(5)(P)°	Press release announcing US antitrust approval, dated August 27, 2007.
(a)(5)(Q)°	Press release announcing completion of loan syndication for financing of Alcan acquisition, dated August 30, 2007.
(a)(5)(R)°	Press release announcing Canadian Competition Act clearance, dated August 30, 2007.
(a)(5)(S)°	Press release announcing Rio Tinto plc Extraordinary General Meeting, dated September 14, 2007.
(a)(5)(T)°	Notice of extension of the Offer, dated September 17, 2007.
(a)(5)(U)°	Letter to shareholders of Alcan announcing the extension of the Offer, dated September 17, 2007.
(a)(5)(V)°	Press release announcing the extension of the Offer, dated September 17, 2007.
(a)(5)(W)°	Press release announcing approval of the acquisition of Alcan by Rio Tinto shareholders, dated September 28, 2007.
(a)(5)(X)°	Press release announcing European competition clearance, dated October 2, 2007.
(a)(5)(Y)°	Press release announcing Australian Competition & Consumer Commission clearance, dated October 3, 2007.
(a)(5)(Z)°	Press release announcing French Government approval, dated October 4, 2007.
(a)(5)(AA)°	Press release announcing Exon-Florio clearance received, dated October 5, 2007.
(a)(5)(BB)°	Press release announcing Australian Foreign Investment Review Board approval, dated October 9, 2007.
(a)(5)(CC)°	Press release announcing Proposed Aluminium Business Executive Management Team, dated October 10, 2007.
(a)(5)(DD)°	Press release announcing receipt of Investment Canada Act approval, dated October 18, 2007.
(a)(5)(EE)°	Joint press release by Rio Tinto and Alcan, dated October 18, 2007, announcing receipt of regulatory approvals.
(a)(5)(FF)°	Advertisement dated October 19, 2007
(a)(5)(GG)	Press release announcing changes to the Rio Tinto Board of Directors, dated October 24, 2007.
(a)(5)(HH)	Press release announcing the commencement of the Subsequent Offering Period, dated October 23, 2007.
(b)(1)°	Facility Agreement, dated July 12, 2007, among Rio Tinto, Credit Suisse, Deutsche Bank AG, London Branch, The Royal Bank of Scotland plc, and Societe Generale.

(d)(1)°	Support Agreement, dated July 12, 2007, among Alcan, the Offeror and Rio Tinto.
(d)(2)°	English language translation of undertakings and confirmations made by Rio Tinto and Offeror to the Government of Quebec and Alcan, dated July 11, 2007.
(d)(3)°	Confidentiality Agreement, dated April 11, 2007 between Alcan and Rio Tinto.
(d)(4)°	Amendment to Confidentiality Agreement, dated June 25, 2007.
(d)(5)°	Standstill Agreement, dated June 13, 2007, between Alcan and Rio Tinto.
(d)(6)°	Amendment to Support Agreement, dated July 20, 2007, among Alcan, the Offeror and Rio Tinto.
(g)°	None.
(h)°	None.

°

Previously filed with the SEC.

QuickLinks

ITEM 12. EXHIBITS
SIGNATURE
EXHIBIT INDEX

EX-99.(A)(5)(GG)

Exhibit (a)(5)(GG)

News release…

Date: 24 October 2007

Ref: PR563g

Rio Tinto Board changes

The boards of Rio Tinto plc and Rio Tinto Limited are pleased to announce that, following the acquisition of Alcan Inc, Yves Fortier, Paul Tellier and Dick Evans have been appointed as directors with effect from 25 October 2007.

Yves Fortier, currently chairman of the board of Alcan, and Paul Tellier, currently a non- executive director of Alcan, become non executive directors of Rio Tinto.  Yves joins the Nominations Committee and the Committee on Social and Environmental Accountability.  Paul joins the Audit Committee and the Remuneration Committee.

Dick Evans, the current Alcan chief executive officer, becomes an executive director of Rio Tinto and the chief executive of the combined aluminium group, Rio Tinto Alcan, based in Montreal and will report directly to Rio Tinto’s chief executive, Tom Albanese.

Commenting on the appointments, Paul Skinner, chairman, said “I am very pleased to welcome Yves, Paul and Dick to the Rio Tinto board.  They will play key roles in providing important continuity during the integration of Alcan and bring valuable new perspectives, particularly in relation to Canada, to our board.”

As announced at the Rio Tinto 2007 annual general meetings , Sir Richard Sykes, currently the senior non executive director, will retire at the conclusion of the 2008 annual general meetings.  Andrew Gould, currently chairman of the Audit Committee, will become the senior non executive director on Sir Richard’s retirement and will become chairman of the Remuneration Committee.  Sir David Clementi will replace Andrew Gould as chairman of the Audit Committee.  These latter changes will take effect from the conclusion of the 2008 annual general meetings.

Notes to editors

Yves Fortier, aged 72, was Ambassador and Permanent Representative of Canada to the United Nations from 1988 to 1992. He is chairman and a senior partner of the law firm Ogilvy Renault.  He has been a director of Alcan since 2002 and is currently the chairman of the board.  Yves is also a non executive director of NOVA Chemicals Corporation, and was governor of Hudson’s Bay Company from 1998 to 2006, a director of the Royal Bank of Canada from 1992 to 2005 and trustee of the International Accounting Standards Committee from 2000 to 2006.

Cont…/

Rio Tinto plc  6 St James’s Square  London SW1Y 4LD

Telephone 020 7930 2399  Fax 020 7930 3249

REGISTERED OFFICE:  6 St James’s Square  London SW1Y 4LD  Registered in England No. 719885

Paul Tellier, aged 68, was Clerk of the Privy Council Office and Secretary to the Cabinet of the Government of Canada from 1985 to 1992 and was president and chief executive officer of the Canadian National Railway Company from 1992 to 2002.  Until December 2004, he was president and chief executive officer of Bombardier Inc.  He has been a non executive director of Alcan since 1998.  Paul is also a director of McCain Foods, Bell Canada, BCE Inc. and the advisory board of General Motors of Canada.  He is also a strategic advisor to Société Générale (Canada).

Dick Evans, aged 60, held senior management positions with Kaiser Aluminium & Chemical Corporation before joining Alcan in 1997 where he has held several senior management positions including executive vice president, Office of the President. He has been president and chief executive officer of Alcan since March, 2006.  Dick is also a non executive director of Bowater Inc. and the International Aluminium Institute

.

For further information, please contact:

Media Relations, London Christina Mills Office: +44 (0) 20 8080 1306 Mobile: +44 (0) 7825 275 605 Nick Cobban Office: +44 (0) 20 8080 1305 Mobile: +44 (0) 7920 041 003	Media Relations, Australia Ian Head Office: +61 (0) 3 9283 3620 Mobile: +61 (0) 408 360 101 Amanda Buckley Office: +61 (0) 3 9283 3627 Mobile: +61 (0) 419 801 349
Investor Relations, London Nigel Jones Office: +44 (0) 20 7753 2401 Mobile: +44 (0) 7917 227 365 David Ovington Office: +44 (0) 20 7753 2326 Mobile: +44 (0) 7920 010 978	Investor Relations, Australia Dave Skinner Office: +61 (0) 3 9283 3628 Mobile: +61 (0) 408 335 309 Investor Relations, North America Jason Combes Office: +1 (0) 801 685 4535 Mobile: +1 (0) 801 558 2645

Email: questions@riotinto.com

Website: www.riotinto.com

High resolution photographs available at: www.newscast.co.uk

Additional information

The offer to purchase all of the issued and outstanding common shares of Alcan for US$101 per common share in a recommended, all cash transaction (the “Offer”) is being made by Rio Tinto Canada Holding Inc. (the “Offeror”), an indirect wholly-owned subsidiary of Rio Tinto. The address of the Offeror is 770 Sherbrooke Street West, Suite 1800, Montreal, Quebec, H3A 1G1.

2

The Offer represents a total consideration for Alcan common shares of approximately US$38.1 billion.

The subsequent offering period has commenced and the Offer is open for acceptance until 6.00 p.m., Canadian Eastern Time, on November 8, 2007, unless extended.

This announcement is for information purposes only and does not constitute or form part of any offer or invitation to purchase, otherwise acquire, subscribe for, sell, otherwise dispose of or issue, or any solicitation of any offer to sell, otherwise dispose of, issue, purchase, otherwise acquire or subscribe for, any security. The Offer (as the same may be varied or extended in accordance with applicable law) is being made exclusively by means of, and subject to the terms and conditions set out in, the offer and takeover bid circular delivered to Alcan and filed with Canadian provincial securities regulators and the United States Securities and Exchange Commission (the “SEC”) and mailed to Alcan shareholders.

The release, publication or distribution of this announcement in certain jurisdictions may be restricted by law and therefore persons in such jurisdictions into which this announcement is released, published or distributed should inform themselves about and observe such restrictions.

In connection with the Offer, an offer and takeover bid circular as well as ancillary documents such as a letter of transmittal and a notice of guaranteed delivery have been filed with the Canadian securities regulatory authorities and the SEC and an Alcan directors’ circular with respect to the Offer has also been filed. A Tender Offer statement on Schedule TO (the “Schedule TO”) and a Solicitation/Recommendation Statement on Schedule 14D-9 (the “Schedule 14D-9”) has also been filed with the SEC.

SHAREHOLDERS OF ALCAN ARE URGED TO READ THE OFFER AND TAKEOVER BID CIRCULAR (INCLUDING THE LETTER OF TRANSMITTAL AND NOTICE OF GUARANTEED DELIVERY), THE SCHEDULE TO (INCLUDING THE OFFER AND TAKEOVER BID CIRCULAR, LETTER OF TRANSMITTAL AND RELATED TENDER OFFER DOCUMENTS) AND THE SCHEDULE 14D-9 AS THEY CONTAIN IMPORTANT INFORMATION ABOUT THE OFFER.

The offer and takeover bid circular as well as other materials filed with the Canadian securities regulatory authorities are available electronically without charge at www.sedar.com. The Schedule TO and the Schedule 14D-9 are available electronically without charge at the SEC’s website, www.sec.gov. Materials filed with the SEC or the Canadian securities regulatory authorities may also be obtained without charge at Rio Tinto’s website, www.riotinto.com.

While the Offer is being made to all holders of Alcan common shares, this announcement does not constitute an offer or a solicitation in any jurisdiction in which such offer or solicitation is unlawful. The Offer is not being made in, nor will deposits be accepted in, any jurisdiction in which the making or acceptance thereof would not be in compliance with the laws of such jurisdiction. However, the Offeror may, in its sole discretion, take such action as it may deem necessary to extend the Offer in any such jurisdiction.

The Offer is made to holders in France of Alcan common shares admitted to trading on Euronext-Paris. An announcement including the main information relating to the Offer documents has been prepared and released pursuant to article 231-24 of the AMF General Regulation and contains information relating to how and in which time limit Alcan shareholders residing in France can accept this Offer. The offer document and the announcement prepared pursuant to article 231-24 of the AMF General Regulation, as amended on 17 September 2007, 23 and 24 October 2007 are available free of charge to

3

the holders of Alcan Shares registered with Euroclear France who request it from Citi France, Global Transaction Services, Operations department, 19 le Parvis la Défense 7, 92073 Paris la Défense. They are also available on the internet at the following address: www.computershare.com/Rio-AlcanFrenchofferdocument.

The Offer is made to holders in Belgium of Alcan common shares and/or certificates admitted to trading on Euronext Brussels (the “IDRs”). A Belgian supplement, addressing issues specific to holders of Alcan common shares and/or IDRs in Belgium (the “Belgian Supplement”) was approved by the Belgian Banking, Finance and Insurance Commission (the “BFIC”) on 2 August 2007. A notice of extension of the Offer was approved by the BFIC on 18 September 2007 (the “First Supplement”). A second notice of extension of the Offer was approved by the BFIC on 23 October 2007 (the “Second Supplement”).  The offer document, the Belgian Supplement , the First Supplement and the Second Supplement are available free of charge to the investors in Belgium who request it from the Belgian branch of Citibank International plc, Department GTS Operations, 4th floor, boulevard Général Jacques 263G, 1050 Brussels. They are also available on the internet at the following address: www.computershare.com/Rio-AlcanBelgianofferdocument

4

EX-99.(A)(5)(HH)

Exhibit (a)(5)(HH)

News release…

Date: 23 October 2007

Rio Tinto Offer for Alcan successful — Offer extended to November 8, 2007

Rio Tinto today announces that approximately 298,759,000 common shares of Alcan Inc. (which represent approximately 79.41% of the outstanding shares on a fully diluted basis) have been validly deposited and taken up under the offer by Rio Tinto Canada Holding Inc. (“RTCH”) to acquire all the shares of Alcan (the “Offer”).  RTCH has also received notices of guaranteed delivery covering approximately an additional 21,336,000 Alcan common shares (which represent approximately 5.67% of the outstanding shares on a fully diluted basis).

All of the conditions of the Offer have been satisfied and the initial offering period, which was extended until October 23, 2007, is now closed for acceptance.  RTCH has taken up all the Alcan shares deposited under the Offer and those shares may no longer be withdrawn.  Payment for the deposited shares will be made to the depositary on October 25, 2007.  The shares covered by notices of guaranteed delivery will be taken up when the certificates representing them are delivered.

RTCH has extended the Offer until 6:00 P.M. (Canadian Eastern Time) on November 8, 2007 by commencing a subsequent offering period (the “Subsequent Offering Period”) to allow those Alcan shareholders who have not already deposited their shares under the Offer the chance to do so.  They will receive US$101 per share as was offered during the initial offering period.  A notice of extension will be mailed promptly.  RTCH will immediately take up and promptly pay for all Alcan shares validly deposited under the Offer during the Subsequent Offering Period.

Paul Skinner, chairman, Rio Tinto said: “We have been working towards our offer for Alcan becoming unconditional and have now passed the final milestone, with more than two thirds of Alcan shareholders having tendered their shares. This landmark deal will contribute significantly to Rio Tinto’s strategy of creating shareholder value through building a portfolio of globally-leading, high quality, long life, low cost assets.”

Tom Albanese, chief executive, Rio Tinto, said “We now look forward to combining Alcan’s excellent assets with our own aluminium operations to create the world’s leading aluminium producer, to be known as Rio Tinto Alcan.  The outlook for aluminium remains strong and the prospects for Rio Tinto Alcan are excellent. Rio Tinto Alcan will be a strong operational platform to pursue new growth opportunities in aluminium.”

If RTCH acquires more than 90% of the Alcan shares, upon expiry of the Offer, it intends to acquire all shares it does not then own by way of statutory compulsory acquisition pursuant to the Canada Business Corporations Act.

Rio Tinto plc  6 St James’s Square  London SW1Y 4LD

Telephone 020 7930 2399  Fax 020 7930 3249

REGISTERED OFFICE:  6 St James’s Square  London SW1Y 4LD  Registered in England No. 719885

If permitted by applicable law, RTCH intends to cause Alcan to cease to be a reporting issuer under Canadian securities legislation and to apply to delist the Alcan common shares from the Toronto Stock Exchange, the New York Stock Exchange, the London Stock Exchange, the SWX Swiss Exchange, Euronext Paris and Euronext Brussels (with respect to the international depositary receipts) and to cause the Alcan common shares to be deregistered under the US Securities and Exchange Act of 1934 as soon as practicable after the completion of the Offer.

About Rio Tinto

Rio Tinto is a leading international mining group headquartered in the UK, combining Rio Tinto plc, a London listed company, and Rio Tinto Limited, which is listed on the Australian Securities Exchange.

Rio Tinto’s business is finding, mining, and processing mineral resources. Major products are aluminium, copper, diamonds, energy (coal and uranium), gold, industrial minerals (borax, titanium dioxide, salt, talc) and iron ore. Activities span the world but are strongly represented in Australia and North America with significant businesses in South America, Asia, Europe and southern Africa.

Cont…

2

For further information, please contact:

Media Relations, London Christina Mills Office: +44 (0) 20 8080 1306 Mobile: +44 (0) 7825 275 605 Nick Cobban Office: +44 (0) 20 8080 1305 Mobile: +44 (0) 7920 041 003	Media Relations, Australia Ian Head Office: +61 (0) 3 9283 3620 Mobile: +61 (0) 408 360 101 Amanda Buckley Office: +61 (0) 3 9283 3627 Mobile: +61 (0) 419 801 349
Investor Relations, London Nigel Jones Office: +44 (0) 20 7753 2401 Mobile: +44 (0) 7917 227 365 David Ovington Office: +44 (0) 20 7753 2326 Mobile: +44 (0) 7920 010 978	Investor Relations, Australia Dave Skinner Office: +61 (0) 3 9283 3628 Mobile: +61 (0) 408 335 309 Investor Relations, North America Jason Combes Office: +1 (0) 801 685 4535 Mobile: +1 (0) 801 558 2645

Email: questions@riotinto.com

Website: www.riotinto.com

High resolution photographs available at: www.newscast.co.uk

Additional information

The offer to purchase all of the issued and outstanding common shares of Alcan for US$101 per common share in a recommended, all cash transaction (the “Offer”) is being made by Rio Tinto Canada Holding Inc. (the “Offeror”), an indirect wholly-owned subsidiary of Rio Tinto.  The address of the Offeror is 770 Sherbrooke Street West, Suite 1800, Montreal, Quebec, H3A 1G1.  The Offer represents a total consideration for Alcan common shares of approximately US$38.1 billion.

The subsequent offering period has commenced and the Offer is open for acceptance until 6.00 p.m., Canadian Eastern Time, on November 8, 2007, unless extended.

This announcement is for information purposes only and does not constitute or form part of any offer or invitation to purchase, otherwise acquire, subscribe for, sell, otherwise dispose of or issue, or any solicitation of any offer to sell, otherwise dispose of, issue, purchase, otherwise acquire or subscribe for, any security. The Offer (as the same may be varied or extended in accordance with applicable law) is being made exclusively by means of, and subject to the terms and conditions set out in, the offer and takeover bid circular delivered to Alcan and filed with Canadian provincial securities regulators and the United States Securities and Exchange Commission (the “SEC”) and mailed to Alcan shareholders.

The release, publication or distribution of this announcement in certain jurisdictions may be restricted by law and therefore persons in such jurisdictions into which this announcement is released, published or distributed should inform themselves about and observe such restrictions.

3

In connection with the Offer, an offer and takeover bid circular as well as ancillary documents such as a letter of transmittal and a notice of guaranteed delivery have been filed with the Canadian securities regulatory authorities and the SEC and an Alcan directors’ circular with respect to the Offer has also been filed. A Tender Offer statement on Schedule TO (the “Schedule TO”) and a Solicitation/Recommendation Statement on Schedule 14D-9 (the “Schedule 14D-9”) has also been filed with the SEC.

SHAREHOLDERS OF ALCAN ARE URGED TO READ THE OFFER AND TAKEOVER BID CIRCULAR, AS AMENDED (INCLUDING THE LETTER OF TRANSMITTAL AND NOTICE OF GUARANTEED DELIVERY), THE SCHEDULE TO (INCLUDING THE OFFER AND TAKEOVER BID CIRCULAR, LETTER OF TRANSMITTAL AND RELATED TENDER OFFER DOCUMENTS) AND THE SCHEDULE 14D-9 AS THEY CONTAIN IMPORTANT INFORMATION ABOUT THE OFFER.

The offer and takeover bid circular as well as other materials filed with the Canadian securities regulatory authorities are available electronically without charge at www.sedar.com. The Schedule TO and the Schedule 14D-9 are available electronically without charge at the SEC’s website, www.sec.gov. Materials filed with the SEC or the Canadian securities regulatory authorities may also be obtained without charge at Rio Tinto’s website, www.riotinto.com.

While the Offer is being made to all holders of Alcan common shares, this announcement does not constitute an offer or a solicitation in any jurisdiction in which such offer or solicitation is unlawful. The Offer is not being made in, nor will deposits be accepted in, any jurisdiction in which the making or acceptance thereof would not be in compliance with the laws of such jurisdiction. However, the Offeror may, in its sole discretion, take such action as it may deem necessary to extend the Offer in any such jurisdiction.

The Offer is made to holders in France of Alcan common shares admitted to trading on Euronext-Paris. An announcement including the main information relating to the Offer documents has been prepared and released pursuant to article 231-24 of the AMF General Regulation and contains information relating to how and in which time limit Alcan shareholders residing in France can accept this Offer. The offer document and the announcement prepared pursuant to article 231-24 of the AMF General Regulation, as amended on 17 September 2007, 23 and 24 October 2007, are available free of charge to the holders of Alcan Shares registered with Euroclear France who request it from Citi France, Global Transaction Services, Operations department, 19 le Parvis la Défense 7, 92073 Paris la Défense. They are also available on the internet at the following address: www.computershare.com/Rio-AlcanFrenchofferdocument.

The Offer is made to holders in Belgium of Alcan common shares and/or certificates admitted to trading on Euronext Brussels (the “IDRs”). A Belgian supplement, addressing issues specific to holders of Alcan common shares and/or IDRs in Belgium (the “Belgian Supplement”) was approved by the Belgian Banking, Finance and Insurance Commission (the “BFIC”) on 2 August 2007. A first notice of extension of the Offer was approved by the BFIC on 18 September 2007 (the “First Supplement”).  A second notice of extension of the Offer was approved by the BFIC on 23 October 2007 (the “Second Supplement”).  The offer document, the Belgian Supplement, the First Supplement and the Second Supplement are available free of charge to the investors in Belgium who request it from the Belgian branch of Citibank International plc, Department GTS Operations, 4th floor, boulevard Général Jacques 263G, 1050 Brussels. They are also available on the internet at the following address: www.computershare.com/Rio-AlcanBelgianofferdocument.

4