BP says it plans a share buyback of at least $4 billion, using the proceeds from the sale of its half of its Russian joint venture to Rosneft.

The move is part of efforts to reward BP investors whose holdings were badly hit by the 2010 Deepwater Horizon disaster and the energy group's travails in Russia.

Last week BP agreed to a $4.5 billion settlement to resolve criminal charges relating to the Gulf disaster, in which a rig BP was leasing blew up, killing 11 men and triggering the worst oil spill in US history. The deal includes a fine of $1.3 billion, the largest financial penalty ever imposed by US authorities. The company also pleaded guilty to 14 criminal charges brought by the department of justice, including 11 counts of manslaughter.

The deal with the department was welcomed by some investors who are keen to see a resolution of BP's Gulf-related problems. (Copyright The Financial Times Limited 2012)