Russia to pull helicopters from South Sudan

* President Medvedev decrees withdrawal after U.N. Sudan mission ends

* Africa envoy's spokeswoman says security concerns not involved

* U.N. diplomats say Russia's refusal to fly behind slow deployment

By Steve Gutterman

MOSCOW, Jan 24 (Reuters) - Russia will withdraw its helicopters and personnel servicing the United Nations peacekeeping force in South Sudan, the Kremlin said on Tuesday, a move that will cause problems for the stretched mission.

The move followed expressions of concern by Russian diplomats over security in South Sudan, including attacks on helicopters operated by Russia's military.

But Varvara Paal, spokeswoman for Russian President Dmitry Medvedev's Africa envoy Mikhail Margelov, said the withdrawal had nothing to do with security.

"The Russian contingent of peacekeepers made a meaningful contribution to the process of the peaceful division of the state (Sudan), which ended in July of last year," Margelov said in a statement.

The U.N. Mission in Sudan, known as UNMIS, ended shortly after South Sudan became independent last July under a 2005 peace pact that ended decades of civil war, and the Russian contingent then worked with a new U.N. mission established in South Sudan.