European Union foreign ministers will condemn on Monday Russia's air strikes on Western-backed rebels in Syria and warn they risk prolonging the conflict, according to a draft statement seen by Reuters.

"The recent Russian military attacks that go beyond Dae'sh and other UN-designated terrorist groups, as well as on the moderate opposition, are of deep concern, and must cease immediately," the draft prepared by EU ambassadors said, referring to Islamic State militants.

EU foreign ministers were meeting in Luxembourg on Monday.