BP has unveiled an "historic" agreement with the Russian government in a £10 billion deal which will open up unexplored reserves in the Arctic.

The "groundbreaking" global alliance will see the UK oil giant own 9.5 per cent of Russian government-owned Rosneft's shares, while Rosneft will take a 5 per cent stake in BP.

Speaking at the signing ceremony in central London on Friday night, BP chief executive Bob Dudley said: "I do believe this is a historic moment for BP, for our industry and I believe for Russia and the wider world of energy globally."

The move suggests BP now intends to focus more towards interests in the east, following a torrid year in North America.

But Mr Dudley denied BP was "turning to the east" in the wake of the Gulf of Mexico disaster.

The oil spill, which followed the explosion on the Deepwater Horizon rig, cost the company tens of billions of pounds.

City analysts said the tie-up would leave BP well-placed to capitalise on Russian oil interests, but may risk upsetting US investors.