Syrian rebels seized most of a military airport in southern Sweida province on Thursday, their first such advance in the regime-controlled region, a spokesman told AFP.

"The Southern Front has liberated Al-Thaala military airport and is carrying out mopping-up operations against remaining forces," the alliance's spokesman Major Essam al-Rayes told AFP.

The Syrian Observatory for Human rights monitor confirmed the rebel advance, but Syrian state television said reports of the base's capture were untrue.