REFILE-Fortescue up 5 pct on report Teck buying shares

MELBOURNE Feb 13 (Reuters) - Shares in Australia's Fortescue Metal Group rose 5 percent on Monday on a report Canadian metals and coal miner Teck Resources may be building a stake in Australia's third-largest iron ore producer.

Talk of Teck positioning itself in Fortescue comes amid speculation that the proposed $90 billion marriage of Glencore and Xstrata may lead to a new force pushing into iron ore.

The iron ore miner's stock surged as much as 5.3 percent to a five-month high of A$5.52, valuing the group at A$17.2 billion, after the Australian Financial Review reported Teck was behind the buying, before closing up 5 percent at A$5.50.

Fortescue shares had risen 5.7 percent on Feb 6 after a mystery buyer snapped up around 3 percent of the stock, believed previously held by U.S. holding group Leucadia.

Teck is one of the world's top exporters of metallurgical coal, one of the key ingredients in steelmaking, but has no iron ore, the other key raw material in steel largely controlled by Brazil's Vale, Rio Tinto and BHP Billiton .

Xstrata has an open desire to mine iron ore, underlined in 2009 by its attempt to buy mining giant AngloAmerican. But a scarcity of major discoveries lately and a near-oligopoly among mining giants Vale, Rio Tinto and BHP Billiton has so far kept iron ore out of its reach.

Iron ore sells for around $142 a tonne to China, the world's top buyer of the steelmaking commodity thanks to the mass urbanisation underway there, and only costs about $20-$30 a tonne to mine.

Australia alone provides almost half of China's iron ore imports, with BHP Billiton, Rio Tinto and Fortescue the main suppliers.

Billionaire Andrew Forrest, who founded Fortescue in April 2003, is the largest shareholder, holding about 30 percent of the firm. Hunan Valin Hunan Valin, a Chinese state-owned steelmaker is second-ranked, with 14.72 percent, making it a difficult target unless one of the top two sell out.

Chinese sovereign wealth fund China Investment Corp holds 17 percent of Teck.

At one time the Canadian firm mined zinc in Australia, but shut its operations in 2008. In the U.S. state of Alaska, Teck owns the world's largest zinc mine, Red Dog.