LONDON/MOSCOW, December 19 (WNM/Reuters/Ron Bousso/Darya Korsunskaya/Dmitry Zhdannikov) - Incoming Chief Executive Bernard Looney will not take up either of BP's seats on the board of Rosneft when he takes over in February because of the complexity of the relationship with the Russian oil giant, five company sources said.

Under an arrangement between Looney and outgoing Chief Executive Bob Dudley, Dudley will keep one of the seats when he retires in March, the sources said. Guillermo Quintero, a Venezuelan national who is also a former BP executive and has ties to the South American country's national oil company PDVSA, will keep the other seat, they said.

The sources said Rosneft had been informed of the arrangement but did not say how long it was expected to last. BP owns nearly a fifth of Rosneft, its biggest foreign investment and the source of a third of its total output.

"Dudley will stay on the board of Rosneft because the relationship between BP and Moscow is very complicated," a senior BP official told Reuters.

Looney's decision not to take either of the board seats has not been previously reported. Dudley said in October he would stay on the Rosneft board after retiring in March, but did not explain why.

"With his unrivalled experience of both the international oil industry and Russia, Bob will continue to provide valuable experience on the Rosneft Board," BP said in a statement to Reuters. Rosneft did not reply to a written request for comment.