UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D/A

Under the Securities Exchange Act of 1934

(Amendment No. 14)*

(Name of Issuer)

(Title of class of securities)

(CUSIP Number)

Ben Mathews

Rio Tinto plc

2 Eastbourne Terrace

London W2 6LG

United Kingdom

+44 (0) 20 7781 2058

(Name, Address and Telephone Number of Person Authorised to Receive Notices and Communications)

with copy to:

Thomas B. Shropshire, Jr.

Linklaters LLP

One Silk Street

London EC2Y 8HQ

United Kingdom

+44 (0) 20 7456 3223

(Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.  ¨

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits.

See § 240.13d-7 for other parties to whom copies are to be sent.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

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Item 1. Security and Issuer

This Amendment No. 14 to Schedule 13D amends and supplements the statement on Schedule 13D originally filed by Rio Tinto plc (“Rio Tinto”) and Rio Tinto International Holdings Limited (“RTIH”) on November 3, 2006, and amended on September 12, 2007, October 26, 2007, January 7, 2008, April 10, 2008, October 30, 2009, March 4, 2010, July 7, 2010, September 13, 2010, December 14, 2010, February 4, 2011, June 28, 2011, August 24, 2011 and September 27, 2011 (as amended and supplemented, the “Schedule 13D”) with the Securities and Exchange Commission (the “SEC”), relating to the common shares, without par value (the “Shares”), of Ivanhoe Mines Ltd., a corporation continued under the laws of the Yukon Territory, Canada (the “Company”). This Amendment No. 14 is being filed to update Rio Tinto and RTIH’s intentions with regard to the Company, further to a successful arbitration against the Company in respect of the Company’s shareholder rights plan.

Item 4. Purpose of Transaction

Item 4 of the Schedule 13D is supplemented as follows and should be read in conjunction with the existing Item 4 disclosure previously filed:

From January 19, 2012, Rio Tinto and RTIH will no longer be subject to a standstill agreement with the Company. Thereafter, depending upon their assessment of the Company’s business, prospects and financial condition, the market for the Shares, general economic and tax conditions and other factors, Rio Tinto or RTIH may seek opportunities to increase their shareholding in the Company to a majority position, but currently have no intention of making a full takeover bid for the Shares. Rio Tinto and RTIH reserve the right to change their intentions in the future.

Item 7. Materials to be Filed as Exhibits

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SIGNATURES

After reasonable inquiry and to the best of my knowledge and belief, each of the undersigned certifies that the information set forth in this statement is true, complete and correct.

Dated: December 16, 2011

Rio Tinto plc

Rio Tinto International Holdings Limited

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SCHEDULE A

The response set forth in Schedule A of the Schedule 13D is hereby amended and restated in its entirety with the information below:

Rio Tinto plc

Directors and Executive Officers

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EXHIBIT INDEX

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EXHIBIT A

JOINT FILING AGREEMENT

The undersigned hereby agree that the Statement on Schedule 13D, dated November 3, 2006, with respect to the common shares, without par value, of Ivanhoe Mines Ltd. is, and any amendments thereto executed by each of us shall be, filed on behalf of each of us pursuant to and in accordance with the provisions of Rule 13d-1(k)(1) under the Securities and Exchange Act of 1934, as amended, and that this Agreement shall be included as an Exhibit to the Schedule 13D and each such amendment. Each of the undersigned agrees to be responsible for the timely filing of the Schedule 13D and any amendments thereto, and for the completeness and accuracy of the information concerning itself contained therein. This Agreement may be executed in any number of counterparts, all of which taken together shall constitute one and the same instrument.

IN WITNESS WHEREOF, the undersigned have executed this Agreement as of the 3rd day of November, 2006.