The board of Russia's third-largest oil producer, TNK-BP , has approved an additional $1.25 billion dividend payout to shareholders, a TNK-BP spokesman said on Sunday.

A source familiar with the situation told Reuters the additional payout for the first half of 2011 was approved at a board meeting on Friday. On top of $4.2 billion already paid this year, it will bring total payments to $5.5 billion, the source said.

BP owns half of TNK-BP, and the other half is controlled by the Russia-connected consortium AAR.

Another source said former BP Chief Executive Tony Hayward had resigned from the TNK-BP board due to other commitments.

Since being forced out of BP in the wake of the Gulf of Mexico oil spill, Hayward has taken on a variety of roles executive and non-executive roles, including founding a $4 billion Kurdistan focused exploration vehicle.

(Reporting by Vladimir Soldatkin and Tom Bergin in London; editing by Tim Pearce and Diane Craft)