Nafta Moscow, the investment vehicle of Russian tycoon Suleiman Kerimov, is in talks to purchase 50% plus one share in state-owned Belarussian fertilizer producer Belaruskali for $15 billion, a source familiar with the situation said on Wednesday.      

The Belarussian government declined to comment.       

A sale, if completed, would at a stroke ease a financial crisis gripping the former Soviet state on Russia's western border that was forced to devalue its currency after a balance of payments crunch.       

Belarus received a $3 billion bailout loan from a Russia-led regional fund last weekend and has turned to the International Monetary Fund for further financial assistance.       

Both Russia and the IMF have urged Belarus to sell off state assets to raise revenue and reform its Soviet-style economy, where 70% of output comes from the state sector.       

Belaruskali has long been seen as the state's most lucrative asset, but President Alexander Lukashenko said in January that no more than 25% of the company would be offered for sale.       

Belaruskali and Russia's Uralkali, in which Kerimov is a major shareholder, sell their output via the Belarusian Potash Co (BPC) joint venture, which controls more than 30% of global exports.