UPDATE 2-Russian tycoons agree to set up mining giant

(Adds Rusal, analysts comments, byline)

By Polina Devitt and Aleksandras Budrys

MOSCOW, May 28 (Reuters) - Russian metals tycoons Vladimir Potanin and Alisher Usmanov agreed on Wednesday on to swap assets and invited the owner of aluminum giant RUSAL to join them to create the world's mining and metals leader.

The agreement could further complicate plans by RUSAL to win control of metals major Norilsk (GMKN.MM). Analysts said that should RUSAL agree to the triple merger, the combined firm would rival global leader BHP Billiton's (BHP.N) size and market value of $150 billion.

Potanin's holding company Interros and Usmanov's Gallagher said Usmanov would buy up to 10 percent in Norilsk Nickel, the world's top producer of nickel and platinum group metal palladium, in which Potanin holds 30 percent.

Interros will in turn buy up to 25 percent-plus-one-share in Metalloinvest, Russia's largest iron ore miner and a steel producer, controlled by Usmanov.

The statement came only hours after a statement from Norilsk that it had suspended merger talks with Metalloinvest because the latter plans an IPO.

Prokhorov sold 25 percent-plus-two-shares in Norilsk to RUSAL, controlled by Russia's richest man Oleg Deripaska, in April.

Potanin and Usmanov said they wanted to create a global leader in the sector in the next five years with investments estimated at $50 billion to $60 billion.

MERGER TO CREATE PREMIUM

Deripaska has said he considered RUSAL's purchase into Norilsk as strategic and could not exclude a full merger.

But he said earlier this year the idea of a RUSAL-Norilsk-Metallionvest merger needed more analysis and proper valuations.

Russian companies, war chests overflowing from a long-running boom in energy and commodities, have been banding together to increase their stake in global markets, tacitly encouraged by the Kremlin.

RUSAL said in a statement it hoped that all decisions regarding Norilsk would be approved by Norilsk's board, which RUSAL will join soon.

RUSAL also said all decisions should be taken with the aim of raising the company's value and declined further comment.

Yuri Vlasov, an analyst at Renaissance Capital, said a full merger of three firms was now fully in the hands of RUSAL because any major deal needs 75 percent of votes of Norilsk.