Russia will not stop its air strikes on Syria until armed groups, such as al Qaeda's wing there, are defeated, Russian Foreign Minister Sergei Lavrov said on Wednesday.

On Tuesday, U.S. Secretary of State John Kerry said that Russia should stop bombing opposition forces in Syria now that U.N.-led peace talks have started.

"Russian strikes will not cease until we really defeat terrorist organisations like Jabhat al-Nusra. And I don't see why these air strikes should be stopped," he said at a news conference in Oman's capital Muscat.

Lavrov also said it would be difficult to impose a ceasefire unless Syria's border with Turkey was secured to prevent smuggling and the movement of fighters.

"Regarding a ceasefire, we have pragmatic ideas and we talked with the Americans who head the Syria support group and we look forward to discussing these ideas at the meeting on February 11," Lavrov said, referring to the International Syria Support Group that is due to meet in Munich on Feb. 11.