The co-owners of Russian potash miner Uralkali have issued exchangeable unlisted bonds to VTB Capital, a subsidiary of the country's No.2 bank VTB, and to Chengdong Investment Corporation, a subsidiary of China's CIC.

The bonds are due 2014 and exchangeable into 14.5 percent of Uralkali shares, Uralkali said in a statement on Friday.

The world's largest potash miner by output did not specify the value of the transaction. Uralkali's market capitalisation, according to Reuters data, has increased 11 percent for the last six months to reach $22 billion.

Tycoon Suleiman Kerimov was the largest Uralkali shareholder with 18.09 percent stake as of Aug.13. Filaret Galchev owned 10.85 percent, Alexander Nesis controlled 9.94 percent, while two other businessmen owned around 8 percent each.

The issuers of the bonds were Wadge Holdings Limited and Fenguard Limited, special purpose vehicles beneficially owned by the key shareholders of Uralkali, it said on Friday.

It was not the first joint transaction of VTB and CIC. In May they bought 7.5 percent in Polyus Gold, Russia's largest gold producer, for $635 million.