The agreement, which was last night yet to be finalised after weeks of boardroom talks, will get BP out of TNK-BP, the oil explorer it formed with a quartet of Soviet-born billionaires operating as AAR in 2003.
Rosneft is expected to take over BP’s 50 per cent stake in the venture for between $25bn and $28bn (£15.6bn and £17.5bn), with BP netting up to $14bn in cash and a stake of between 15 and 20 per cent in Rosneft itself.
BP is also seeking one or two seats on the board of Rosneft, giving it a direct channel to the firm’s chief executive Igor Sechin, the former deputy Prime Minister of Russia and a close ally of Vladimir Putin.
In a separate deal, Rosneft could end up with full control of TNK-BP by buying out AAR, which has also been in talks to sell up. The firm is believed to have the financing in place for a purchase of this size, which would put it in control of more than half the oil production in Russia.
BP and AAR both made a dash for the exit over the summer, after years of bitter wrangling over TNK-BP that has sparked court cases, $1bn in withheld dividend payments and BP chief executive Bob Dudley chased out of Russia in 2008.
While TNK-BP has paid BP some $19bn in dividends since its inception, growing rifts with AAR culminated in the oligarchs blocking the BP’s first plan to tie up with Rosneft in 2011.