Mining giant Rio Tinto eyes Russia's Uralkali facilities.

A delegation from Anglo-Australian mining giant Rio Tinto is visiting the facilities of one of Russia's largest potash miners Uralkali with a view to purchasing part of the firm, Vedomosti business newspaper said on Wednesday.

The participants in the group that arrived late last week are not known, but Russian billionaire Suleiman Kerimov, who controls Uralkali, flew in to join it on Monday, according to an unnamed source quoted by the paper.

Vedomosti sources say that Rio Tinto refrains from using the term "due diligence" when discussing the visit. However, the mining giant became interested in Uralkali shares in June, immediately after Dmitry Rybolovlev sold his controlling stake to Kerimov, Polymetal head Alexander Nesis and Eurocement head Filaret Galchev.

All the companies involved declined to comment.

A source close to the three owners told Vedomosti that Rio Tinto was prepared to buy 10-15 percent of Uralkali for an estimated $15 billion.

Another source claims that Uralkali's new owners could sell only a small amount of stock in order to repay debts to VTB bank, which loaned each owner $1 billion. The price being discussed with Rio Tinto is 50 percent higher than the market price assessment done for the June deal. A friend of Rybolovlev claims the businessman has no plans to sell his 10 percent of Uralkali just yet.

A source close to one of the company shareholders said Rio Tinto wanted to purchase a stake that would give it a seat on the board of directors. The Uralkali board has nine seats, and a member can be admitted with a 10-11 percent stake.