6-K

QuickLinks -- Click here to rapidly navigate through this document

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

FORM 6-K

Report of Foreign Private Issuer Pursuant to Rule 13a-16 or 15d-16
Under the
Securities Exchange Act of 1934

For July 11, 2006
Commission File No. 1-11284

FALCONBRIDGE LIMITED
(Translation of registrant's name into English)

181 Bay Street, Suite 200, BCE Place,
Toronto, Ontario, Canada M5J 2T3
(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover Form 20-F or Form 40-F.

Form 20-F o Form 40-F ý

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1).

Yes o No ý

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7).

Yes o No ý

Indicate by check mark whether the registrant by furnishing the information contained in this Form is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

Yes o No ý

If "Yes" is marked, indicate below the file number assigned to the registrant in connection with
Rule 12g3-2(b):                              

Furnished herewith is:

Exhibit 99.1 News Release dated July 11, 2006 of Falconbridge Limited regarding "Falconbridge Responds to Announcement by Xstrata".

SIGNATURES

        Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

	FALCONBRIDGE LIMITED (Registrant)
July 11, 2006
	By:	/s/  STEPHEN K. YOUNG Stephen K. Young — Corporate Secretary

Exhibit Index

Exhibit No.	Description
Exhibit 99.1	News Release dated July 11, 2006 of Falconbridge Limited regarding "Falconbridge Responds to Announcement by Xstrata".

QuickLinks

SIGNATURES
Exhibit Index

EX-99.1

Exhibit 99.1

Falconbridge Responds to Announcement by Xstrata
JUL 11, 2006 — 12:52 ET

TORONTO, ONTARIO — (CCNMatthews — July 11, 2006) — Falconbridge Limited (TSX:FAL)(NYSE:FAL) is reviewing the implications of the press release issued today by Xstrata plc indicating that Xstrata intends to increase its offer to purchase for $59 cash per share all of the outstanding common shares of Falconbridge.

The Falconbridge Board of Directors will evaluate the terms of the offer and provide Falconbridge shareholders with a formal response as soon as it has completed its analysis.

Falconbridge Limited is a leading copper and nickel company with investments in fully integrated zinc and aluminum assets. Its primary focus is the identification and development of world-class copper and nickel orebodies. It employs 14,500 people at its operations and offices in 18 countries. Falconbridge's common shares are listed on the New York Stock Exchange (FAL) and the Toronto Stock Exchange (FAL). Falconbridge's website can be found at www.falconbridge.com.

FOR FURTHER INFORMATION PLEASE CONTACT:

Falconbridge Limited
Denis Couture, Senior Vice-President
Investor Relations, Communications and Public Affairs
(416) 982-7020
(416) 982-7242 (FAX)
denis.couture@falconbridge.com
www.falconbridge.com