BP has signed a joint venture with Russian energy firm Rosneft to exploit potentially huge deposits of oil and gas in Russia's Arctic shelf.
The "strategic global alliance" will see the firms exchange expertise in exploring the region.
As part of the deal Rosneft will take 5% of BP's shares in exchange for approximately 9.5% of Rosneft's shares.
It is BP's first deal since the Deepwater Horizon spill last year, which cost it billions.
The BP shares stake is worth just under $8bn (£5bn).
"BP executives see this as the first piece of good news since that disastrous oil spill in the Gulf of Mexico last April," said the BBC's business editor Robert Peston.
But he said the deal was a controversial one, with Russia not seen as an entirely transparent society nor as as a stable place to do business. BBC News
