Russian Prime Minister Dmitry Medvedev raised the spectre of an interminable or a world war if powers failed to negotiate an end to the conflict in Syria and warned against any ground operations by U.S. and Arab forces.

Medvedev, speaking to Germany's Handelsblatt newspaper on the eve of talks between major powers on Syria in Munich, said the United States and Russia must exert pressure on all sides in the conflict to secure a cease-fire.

Asked about Saudi Arabia's offer last week to supply ground troops if a U.S.-led operation were mounted against Islamic State, he said: