A Russian state-owned firm stands to become one of the world's leaders in oil production if it secures a multi-billion dollar deal with BP.
BP said on Friday that it would make an announcement "at the appropriate time" if a deal is struck. Kremlin-backed oil firm Rosneft reportedly made an offer worth around 28 billion dollars (21.5 billion euros).
"If and when BP reaches any agreement, it will make an announcement at the appropriate time," said the statement made to the London Stock Exchange after markets closed Friday.
BP also confirmed that the 90-day period for the submission of a bid expired on Thursday.
BP is looking to sell its share in the troubled Russian joint venture, TNK-BP.
The cash-and-shares deal would give BP between 15 and 20 billion dollars in cash plus a stake of between 10 and 20 percent in Rosneft, reports said.
If approved, it would transform the Russian firm into one of the world's largest oil companies, with daily crude output of more than three million barrels.
Reportedly, the four Russian oligarchs who have been behind the consortium, the AAR, have agreed to sell their 50 percent stake.
A manager of TNK-BP in Moscow was reportedly arrested on Friday on suspicion of fraud. It was unclear whether the arrest was connected with the possible deal between Rosneft and BP.
tm/ccp (AFP, dpa)