LONDON - BP chief executive Bob Dudley is to travel to Moscow next week as part of a trade mission led by Britain's prime minister, David Cameron, as the oil giant battles headwinds in Russia, a source close to the matter said on Tuesday.

BP is Britain's biggest investor in Russia, owning half of TNK-BP, the country's third-largest oil producer, and other investments.

The invitation to accompany Cameron was based on this position, the source said, adding BP's spat with its partners in TNK-BP, who have alleged billions of losses due to BP's failed plan to establish a parallel joint venture, with state-controlled Rosneft, was not on the agenda. ?

Last week, black-clad special forces raided BP's Moscow offices and searched for documents related to the failed Rosneft deal.

BP declined to comment.