BP plc will push ahead with plans to sell its 50% stake in Russian joint venture TNK-BP Ltd. even if its move is met with opposition from its partners in the venture.

Alfa-Access-Renova, the consortium of Russian billionaires that owns the remainder of Russia's biggest independent oil company, might seek to block BP from opening TNK-BP's books to potential buyers, according to a report in the Financial Times.

That would make it difficult for the British oil company to strike a deal for its holding, but falls short of providing the Russian partners with the ability to stop the sale. AAR could, however, use its limited leverage to discourage other bidders while it puts together its own offer. Sources close to AAR have said that the consortium is considering just such a move.

It would likely pit the Russian billionaires against the Russian state. While neither BP nor any other partner has confirmed the names of the interested parties, Reuters reported Monday, June 4, that OAO Rosneftegaz, an energy holding company, was behind the approach for the TNK-BP stake. The Russian government wants to establish the state-controlled group as a global oil player by adding assets to its existing 75% stake in Russian oil major OAO Rosneft and nearly 11% of gas company OAO Gazprom.

BP said Friday that it had received unsolicited approaches for its 50% stake, which analysts said could be worth about $26 billion. TNK-BP accounts for about 30% of BP's production and reserves, while its about $3.8 billion in annual dividends equates to about 20% of the British company's earnings.

BP will not be concerned about offending AAR. The civility of relations between the partners is a distant memory, and the board hasn't met since December, when several directors, including former German Chancellor Gerhard Schröder, quit, reportedly because of disagreements over TNK-BP's intention to sue its British parent.

Mikhail Fridman, who holds a 25% stake in TNK-BP through the AAR consortium, last week told Russian papers that the partnership with BP was unworkable, and he stepped down as CEO of the joint venture.

BP's involvement in TNK-BP has been tumultuous. In 2008 BP's current CEO Bob Dudley was forced to flee Russia and briefly went into hiding when he was ousted as chairman of TNK-BP. Last year, AAR forced BP to drop plans to tie itself to Rosneft when courts agreed that a share exchange and joint exploration program was contrary to TNK-BP's shareholder agreements.

BP did not immediately respond to requests for comment.