Rosneft has closed its purchase of a 50% share in TNK-BP, a move that makes Rosneft the world’s largest publicly traded oil and gas company by hydrocarbon production and reserves.

The purchase was announced in December. The companies announced on March 21 that Rosneft made the final payment to BP, completing the deals.

Rosneft bought half of TNK-BP from the AAR consortium for US $27.73 billion and purchased the remaining half of the shares from BP for $16.8 billion and 12.8% Rosneft shares.

Separately, BP acquired 5.66% of Roseneft shares from OFSC Rosneftegaz. The transaction boosted BP’s holdings in Rosneft to 19.75%.

BP Group Chief Executive Robert Dudley has been nominated as a candidate to join the Rosneft board of directors ahead of completion of the transaction, according to a news release. Electing board members is on the agenda of the company’s 2012 annual general meeting set for June 20, 2013. Dudley is also a member of Rosneft’s steering committee on TNK-BP integration.

Commenting on the BP transaction, Rosneft President and Chairman of the Management Board Igor Sechin, said, “We are delighted to close this transaction ahead of schedule and would like to thank our partners in BP for their cooperation throughout the process. We welcome BP as a strategic investor in Rosneft and look forward to their involvement in forming the future strategic direction of the company through its representation on the Rosneft board of directors.”