SC TO-T/A

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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. 21)

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. 21 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 18, 2007, Rio Tinto issued a press release announcing receipt of approval under the Investment Canada Act for the proposed acquisition of Alcan. On that same date, Rio Tinto and Alcan issued a joint press release announcing receipt of all regulatory approvals required for the closing of the Offer. These press releases have been filed as Exhibit (a)(5)(DD) and Exhibit (a)(5)(EE), respectively, hereto and are incorporated herein by this reference.

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.
(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 18, 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.
(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.

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ITEM 12. EXHIBITS
SIGNATURE
EXHIBIT INDEX

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

Exhibit 99 (a)(5)(DD)

News release…

Date:  18 October 2007

Ref: PR560g

Rio Tinto Offer for Alcan: Investment Canada Act approval received

Rio Tinto has received approval from The Honourable Jim Prentice, Canada’s Minister of Industry, under the Investment Canada Act for the proposed acquisition of Alcan Inc. by a subsidiary of Rio Tinto.

Rio Tinto’s Chief Executive, Tom Albanese, said “This important step recognises that we have committed to bring significant benefits to Canada as a result of this transaction. Rio Tinto has been an investor in Canada for decades and is dedicated to growing the combined Rio Tinto Alcan presence, which will be headquartered in Canada and will be positive for Canadian jobs, investment and research and development.”

Rio Tinto obtained Investment Canada Act approval by demonstrating that its acquisition of Alcan would be of net benefit to Canada. In doing so, Rio Tinto has provided to the Minister several important undertakings in relation to Alcan’s operations and employees in Canada, including establishing the new global aluminium leader’s headquarters in Montréal, ensuring that a majority of Canadian based senior managers are Canadian, creating a shared services hub in Montréal and ensuring robust R&D employment and expenditures. Rio Tinto has also made major capital expenditure commitments on projects such as the AP50 pilot plant in Québec and the Kitimat modernization in British Columbia.

In addition to the chief executive of Rio Tinto Alcan, Dick Evans, Rio Tinto will be appointing two of the Canadian non-executive directors of Alcan to its Board. Further, Rio Tinto will be making significant contributions to Canadian communities, including the creation of a major charitable foundation, demonstrating Rio Tinto’s dedication to Canada.

The undertakings made to the Minister of Industry build on the commitments Rio Tinto has made to the Province of Québec pursuant to the Continuity Agreement.

Rio Tinto’s offer for Alcan is scheduled to expire at 6:00 p.m. Canadian Eastern Time on October 23, 2007. Alcan shareholders are encouraged to tender their shares as soon as possible.

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

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.

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

Alcan contact information:

Media Relations:

Anik Michaud
Tel.: +1-514-848-8151
media.relations@alcan.com Investor Relations:

Ulf Quellmann
Tel.: +1-514-848-8368
investor.relations@alcan.com

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

The Offer is open for acceptance until 6.00 p.m., Canadian Eastern Time, on October 23, 2007, unless extended. The Offer is subject to a number of conditions including valid acceptances by holders of not less than 66 2/3 per cent of Alcan shares on a fully diluted basis and the receipt of various governmental and regulatory approvals. The board of Rio Tinto has approved the transaction. The Offer is expected to close in the fourth quarter of 2007.

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

3

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, 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 notice of extension of the Offer was approved by the BFIC on 18 September 2007. The offer document, the Belgian Supplement and the notice of extension 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

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

Exhibit 99(a)(5)(EE)

News release…

Date: 18 October 2007

Ref: PR561g

Rio Tinto receives all regulatory approvals for the Alcan Offer

All regulatory approvals required for the global closing of the proposed acquisition of Alcan by a subsidiary of Rio Tinto have now been received. The Offer is scheduled to expire at 6:00 p.m. Canadian Eastern Time on October 23, 2007, and Alcan Inc. shareholders are encouraged to tender their shares to the Offer as soon as possible.

Shareholders requiring assistance to tender their shares or who have questions regarding the Offer should contact their broker or Georgeson, the Information Agent for the Offer, at the following numbers:

North American toll free:	1 888 605 7629
European Union free call:	00 800 6540 6540
Australia free call:	1 800 216 071

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.

About Alcan

Alcan Inc. (NYSE, TSX: AL) is a leading global materials company, delivering high quality products and services worldwide. With world-class technology and operations in bauxite mining, alumina processing, primary metal smelting, power generation, aluminum fabrication, engineered solutions as well as flexible and specialty packaging, today’s Alcan is well positioned to meet and exceed its customers’ needs. Alcan is represented by 68,000 employees, including its joint ventures, in 61 countries and regions, and posted revenues of US$23.6 billion in 2006. The Company has featured on the Dow Jones Sustainability Indexes consecutively since 2002. For more information, please visit: www.alcan.com.

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

For further information, please contact:

Rio Tinto:

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

Alcan contact information:

Media Relations:

Anik Michaud
Tel.: +1-514-848-8151
media.relations@alcan.com Investor Relations:

Ulf Quellmann
Tel.: +1-514-848-8368
investor.relations@alcan.com

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

The Offer is open for acceptance until 6.00 p.m., Canadian Eastern Time, on October 23, 2007, unless extended. The Offer is subject to a number of conditions, including valid acceptances by holders of not less than 66 2/3 per cent of Alcan shares on a fully diluted basis.

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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, 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.

3

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 offer document, the Belgian Supplement and the notice of extension 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

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