A Chinese state investment vehicle has taken a 12.5-percent stake in Russia's leading potash producer Uralkali, the company said on Tuesday, in a new sign of China's interest in the fertiliser.

"On 24 September, 2013 the company was notified by Chengdong Investment Corporation that their stake in Uralkali amounts to 12.5 percent," Uralkali said in a statement.

Chengdong Investment Corporation is a subsidiary of China's sovereign wealth fund, China Investment Corporation (CIC).

The increase in the stake was due to the conversion into ordinary shares of bonds held by Chengdong Investment Corporation, Uralkali said.

"Uralkali is not a party to any agreement regarding this transaction," it added.

Uralkali, one of the world's largest potash producers with a share of about 20 percent of global production, has been the focus of intense attention after its chief executive Vladislav Baumgertner was arrested in Belarus in August.

Baumgertner remains in custody in Minsk accused of an illegal scheme to enrich himself and other executives in a case denounced both by Uralkali and the Russian authorities.

Potash is highly sought-after in fast-growing emerging economies as the fertiliser can be used to dramatically increase crop yields.

According to Uralkali, its new shareholder structure means that after the Chinese transaction, 54 percent of shares are in free float and 21.75 percent are owned by Suleiman Kerimov, a Russian tycoon and owner of the Anzhi football club.

Belarussian investigators have also charged Kerimov in the probe in absentia and he is reportedly now keen to offload his shareholding.