Rebels seized a military airport in Syria's northern province of Aleppo on Tuesday, capturing for the first time a fleet of deployable warplanes including MiG fighter jets, a watchdog said.

During their operation to take over the Al-Jarrah aiport, rebels killed, injured or imprisoned some 40 troops, the Britain-based Syrian Observatory for Human Rights said.

"The remainder of the troops pulled out from the airport, leaving behind several warplanes and large amounts of ammunition," Observatory director Rami Abdel Rahman told AFP.

"This is the first time rebels capture warplanes, among them MiG fighter jets," Abdel Rahman said, adding that airports captured in the past by rebels had only "damaged or otherwise unusable" planes left behind by regime troops.

The capture of the Al-Jarrah military airport came a day after Islamist rebels overran the town of Tabqa, situated in the neighbouring province of Raqa, before taking control of the nearby strategic Al-Thawra dam on the Euphrates.

"The rebels' progress in this area has been extremely quick," Abdel Rahman said.

"While the army has full control of parts of Damascus province, the capital and the central province of Hama, it is suffering losses in Homs in the centre, Deir Ezzor in the east, and Aleppo and Raqa in the north," he added.

"There are clashes all over the country, and it is impossible for the army to control every flashpoint."

Activists in Aleppo have told AFP that rebel fighters in the north have shifted their focus in recent weeks to the capture of military airports and bases.

"They are important because they are an instant source of ammunition and supplies, and because their capture means putting out of action the warplanes used to bombard us," Aleppo-based activist Abu Hisham said via the Internet.

The capture of Al-Jarrah airport came just over a month after rebels overran Taftanaz airbase, the largest in northern Syria.

Amateur video shot by rebels overrunning Al-Jarrah on Tuesday and distributed via the Internet showed a fleet of warplanes lining the airport's runways.

"Thank God, Ahrar al-Sham (Islamist rebels) have overrun the military airport" at Al-Jarrah, said an unidentified cameraman who shot a video at the site.

"MiG warplanes are now in the hands of Ahrar al-Sham. And here is the ammunition," the cameraman added, filming two Russian-made fighter jets like those the army has used since last summer to bombard rebel targets.

Meanwhile, clashes raged on Tuesday near other airports in Aleppo province, activists said.

Rebels were targeting Nayrab and Kwayris military airports, as well as Aleppo international airport, which has been closed since January 1, activists said.