MOSCOW (Reuters) - Rosneft (>> Rosneft' NK OAO), the state-owned Russian crude producer which earlier this year bought TNK-BP, announced several senior management appointments on Monday after former TNK-BP executives decided to leave positions they had been offered.

The world's biggest listed crude producer, which paid $55 billion in cash and stock for TNK-BP, said its former head, Eduard Khudainatov, was taking over the production department from Sergei Brezitsky, who had worked at TNK-BP until 2011 prior to being offered the job at Rosneft.

Among the other changes, Marcus Cooper, a veteran of British oil firm BP (>> BP plc) which ended up with almost 20 percent in Rosneft after the TNK-BP deal, will head the Russian firm's trading unit, also taking over from a former TNK-BP employee.

Business daily Vedomosti said last week two former managers of TNK-BP had left Rosneft for "personal reasons", only about two months after moving to new jobs, possibly due to differences in the "corporate culture".

A Rosneft spokesman declined immediate comment on why the former TNK-BP managers had left, while a source at the company said "its working schedule is tougher than at a private firm."

Rosneft is headed by Igor Sechin, a powerful and long-standing ally of Russian President Vladimir Putin. Before taking over Rosneft last year, Sechin, a former military translator, oversaw country's energy sector in the government.

(Reporting by Vladimir Soldatkin; Editing by Mark Potter)

Stocks treated in this article : BP plc, Rosneft' NK OAO, TNK-BP Holding OAO