Billionaire Suleiman Kerimov has agreed to raise his stake in Polyus Gold to 37 percent in a deal that ends an asset split between yet another two Russian billionaires, two sources close to the deal said Friday.

The sources, speaking on condition of anonymity, declined to provide more details of the deal and said it was subject to regulatory approval.

Vedomosti, citing two unidentified sources, reported Friday that Kerimov had spent $1.3 billion building up his stake. He bought 15 percent of Polyus, the country's largest gold miner, from billionaire Vladimir Potanin on Wednesday after acquiring 22 percent from him last month, the report said.

The deal must still be approved by the Federal Anti-Monopoly Service and the Commission on Foreign Investments because the deal is between offshore companies.

Kerimov's investment vehicle, Nafta-Moskva, and Potanin's Interros investment company and Polyus declined to comment.

Industry sources said in March that Kerimov had bought a 20 percent stake in Polyus from Potanin and planned to acquire Potanin's remaining 17 percent.

The gold miner was the last company under the joint control of Potanin and Mikhail Prokhorov, former business partners who announced more than two years ago that they were splitting their varied assets in mining and finance. Prokhorov, who is chairman of Polyus, remains a shareholder.

Last week, Prokhorov disclosed in a regulatory filing that he sold Polyus shares for $103 million on Dec. 25. He held 1.89 percent, or 3.6 million shares, after the deal, it said.

Polyus has gained 76 percent on the MICEX since Dec. 25, and it is also listed in London.

Prokhorov's overall holdings in Polyus were not altered by the sale, an official at his Onexim Group said. He declined to give the size of the stake.

Analysts welcomed the deal, saying it resolved the long-lasting shareholder conflict between Potanin and Prokhorov.

"Kerimov is reportedly a Prokhorov ally, and therefore we would expect him to support Prokhorov in development of the company," UniCredit said in a note.

Troika Dialog said the sale of the stake at $1.3 billion would signal a 60 percent discount to the current price.

"It is logical for Interros to monetize its stake in Polyus Gold at this stage in some shape or form, providing much-needed cash to the holding, especially considering that Mikhail Prokhorov's Onexim Group, with its 30 percent stake, fully controls the operations of the gold company," it said.

Gold, often sought as a safe-haven alternative to equities and currencies during economic strife, has performed better than other metals during the global financial crisis.

Polyus produced about one-fifth of Russia's gold last year.

(Reuters, Bloomberg)