June 30 (Bloomberg) -- Rio Tinto Group, the world's second- largest iron ore producer, rose the most in almost two weeks in London trading after the Financial Times said ArcelorMittal may buy a stake to secure supplies of the steelmaking raw material.

ArcelorMittal could afford to buy a similar size to the 9 percent, $14 billion shareholding acquired in February by Aluminum Corp. of China and Alcoa Inc., the FT reported, citing unidentified people familiar with the matter. Rio, subject of a $171 billion hostile bid from BHP Billiton Ltd., rose 2.8 percent, the largest one-day gain since June 17.

Chief Executive Officer Lakshmi Mittal has also considered buying iron ore assets should antitrust regulators demand their sale as a condition of a tie-up between London-based Rio and BHP, the newspaper said, citing a banker.

``It doesn't make any sense as ArcelorMittal will be just as influential by being a big customer as it would by owning a stake in the company,'' Charlie Dove-Edwin, an analyst at MF Global Securities based in London, said today in a telephone interview. ``I don't think a deal like this could go through.''

Rio increased 166 pence to 6,009 pence in London. The stock has gained 13 percent this year, valuing the company at 89.7 billion pounds ($178.5 billion).

ArcelorMittal declined 88 cents, or 1.4 percent, to 62.80 euros on the Amsterdam Stock Exchange. The shares have advanced 18 percent this year, valuing the company at 91 billion euros.

Haroon Hassan, a spokesman for ArcelorMittal in London, declined to comment, as did Ian Head, a spokesman for Rio in Melbourne.

The European Commission, the European Union's antitrust regulator, is due to say by July 4 whether BHP's bid must proceed to a second-round investigation. The deal is also conditional on regulatory approval in Australia, South Africa and the U.S.

To contact the reporters on this story: Rebecca Keenan in Melbourne at rkeenan5@bloomberg.net; Brett Foley in London at bfoley8@bloomberg.net

Last Updated: June 30, 2008 12:12 EDT