Rosneft seeks $15 bln funding for TNK-BP buy - bankers

* BP, Rosneft brief Putin on talks

* BP wants to leave TNK-BP, stay in Russia

* Rosneft seeks to buy stake, revive BP alliance

* Deal not seen as imminent

By Claire Ruckin and Vladimir Soldatkin

LONDON/MOSCOW, Sept 19 (Reuters) - Russian state oil firm Rosneft is talking to banks about raising $15 billion in debt financing as it inches towards a deal to buy BP's one-half stake in Anglo-Russian oil venture TNK-BP, bankers said on Wednesday.

Rosneft and the British oil company briefed Russian President Vladimir Putin on their negotiations on Tuesday evening, with both playing down expectations of an imminent breakthrough.

Bankers in London said, however, that Rosneft - headed by powerful former deputy premier Igor Sechin - was in talks with 12 to 14 lenders to raise debt financing in the form of a bridge loan, term loans and bonds.

"The company has no outstanding bonds at all and there is clearly a lot of capacity for them to raise this debt," one banker close to the situation told Loan Pricing Corporation, a Thomson Reuters publication.

Rosneft is talking to BP about buying half of TNK-BP, Russia's third-largest oil firm, in a move towards creating a national champion pumping nearly 4 million barrels per day - or two-fifths of output in the world's largest oil producer.

A deal would release BP from a partnership with four Russian billionaires who own the other half of TNK-BP. That could open doors to new opportunities in Russia for the British firm, whose bid to drill for oil in the Arctic with Rosneft was vetoed last year by its local partners.

Independent analysts value the stake at around $25 billion, indicating Rosneft may still have to make up the balance with equity or additional debt if it wants to buy the full BP stake.

Bankers said that $10 billion of the debt financing could be made up of the bridge and term loans, with the rest coming from bond issuance.

Putin met BP chief executive Bob Dudley and chairman Carl-Henric Svanberg and Sechin at his Black Sea retreat in Sochi on Tuesday evening to discuss "broadening" BP's presence in Russia, the Russian leader's spokesman said.

"During the meeting BP reiterated its long-term commitment to Russia and provided assurances that, while the company is looking to exit its investment in TNK-BP, it is not exiting Russia," BP said in a statement issued by its Moscow office.

A Rosneft source said: "I don't expect any breakthrough at the moment."

IRRECONCILABLE DIFFERENCES

BP's joint venture with the quartet of Soviet-born tycoons was created in 2003, costing it $7 billion for 50 percent.

The partnership has been highly profitable but has been riven by shareholder friction, leading BP to put the stake up for sale in June.

Under their shareholder agreement, only the local owners, led by Mikhail Fridman and represented via the AAR consortium, can agree to buy out BP before a mid-October deadline. After that, other suitors may strike a deal.

Sources familiar with the matter say that talks between BP and AAR, which has said it would be willing to pay $10 billion for 25 percent of TNK-BP, have made little progress. AAR has also said it could sell out in exchange for cash and BP stock.

A deal struck in early 2011 for BP to partner with Rosneft in a search for oil in Russia's Arctic offshore and exchange equity stakes was blocked when AAR won a court injunction.

The tycoons later turned down a $32 billion buyout offer from Rosneft and BP for their stake. Arbitration proceedings continue over whether BP violated TNK-BP's shareholder pact, potentially opening the way for significant damages claims.

Fridman quit as TNK-BP CEO in May, and the shareholders have been unable to agree on filling a vacant board post, blocking dividend payments and strategic decisions.

Earlier this month Sechin said Rosneft had taken a time-out in talks to buy the TNK-BP stake to avoid falling foul of the mid-October deadline set by the shareholder pact.

Sources say Sechin's ambition remains undimmed for Rosneft ultimately to acquire outright control of TNK-BP, though he faces some high-profile opposition, including from deputy prime minister Arkady Dvorkovich.