MOSCOW (Reuters) - Russian billionaire Viktor Vekselberg and his co-investors in Sual Partners plan to buy a 12 percent stake in aluminium maker Rusal (0486.HK) held by Mikhail Prokhorov's Onexim group, two sources close to Vekselberg told Reuters.
They did not provide further detail.
Renova group, which manages Vekselberg's assets, Onexim and Rusal declined to comment.
Vekselberg has previously said he planned to complete the deal by the end of October but has not disclosed the size of the stake or its price.
Vedomosti daily earlier on Thursday quoted three sources as saying Vekselberg and his partner Leonard Blavatnik would pay up to $700 million for the stake.
The price would mean a 17 percent premium to the current market price, and the deal is due to close by the end of November, the newspaper added.
Russia's largest lenders Sberbank (SBER.MM) and VTB (VTBR.MM) could provide Sual Partners with a loan to finance the purchase, according to Vedomosti. Both banks did not immediately respond to a Reuters request for comment.
Rusal, the world's second-largest aluminium producer, is controlled by Oleg Deripaska and part-owned by trading group Glencore (GLEN.L).
Onexim and Sual Partners own 17 percent and 15.8 percent in Rusal respectively.
Negotiations about the deal come some six months after Russian law enforcement officials searched Onexim's offices in relation to a tax investigation into an unspecified firm or group.
Vedomosti then reported that Onexim had decided to sell all its assets in Russia, but the group said the report was inaccurate as its "assets are constantly in a state of transition".
Vekselberg's Renova group also saw armed state security agents in ski masks in its Moscow offices in September as Russian law enforcement officers investigating bribery allegations detained two senior executives who work with Vekselberg.
(Reporting by Svetlana Reiter, Polina Devitt and Anastasia Lyrchikova; Editing by David Holmes)