A news flash on state television said the army had so far repelled three attacks on the outskirts of the al-Thala airport, Reuters reported. Rebels said they seized the airbase in a renewed offensive.
The loss of the airport would compound setbacks for Damascus in the area after losing a nearby military base this week.
They also recently denied that a military plane had crashed in southern Syria, according to state television. Rebels said earlier they had shot down a Russian-made MIG jet, Reuters reported. The released video featured what appeared to be a burnt-out plane.
It was shown near the site of fighting around a military airport that rebels have been trying to gain control of since Wednesday.