Heavy fighting over a major military airbase in Sweida, a southern province that is largely under regime control, has continued between a coalition of opposition fighters and government forces, Al Jazeera's Mohammad Noor reported from neighbouring Deraa province.

The clashes on Friday came a day after the Southern Front, a rebel group that controls most of Deraa, took over large parts of the Al-Thalaa base in its first significant advancement in Sweida.

The Syrian Observatory for Human Rights, a UK-based monitoring group that relies on activists on the ground, reported that the fighters withdrew from the base under heavy government fire.

"Opposition fighters withdrew from areas they seized yesterday after heavy regime aerial bombardment and the arrival of reinforcements from the National Defence Forces (pro-regime militia) and Popular Committees," said Observatory chief Rami Abdel Rahman.

Al-Jazeera's correspondent confirmed that Syrian regime forces regained control over western parts of the airport, but noted that the battle was ongoing.

He also said that opposition forces launched several attacks to take control of a town near the army base, and to cut regime supply lines, while the military launched more than seventy air raids on the base and nearby towns, killing and wounding dozens of people.

Syrian state television denied that the airbase had fallen to rebels, and the provincial governor claimed that life was continuing "as normal" in the region.

The Southern Front's advance into Sweida came after the opposition coalition seized one of the largest military bases in Deraa.