Rebels launched assaults yesterday in an attempt to take strategic airports in northern Syria.
It was part of a campaign to fight back against the air power that has given forces loyal to the president, Bashar Al Assad, free rein to bomb rebel-held towns.
Insurgents battled with troops on the perimeter of the Aleppo international airport, besieging the nearby military in an attempt to push through to the airport itself.
At the same time, hundreds of fighters with two Islamist rebel groups, the Jabhat Al Nusra Front and Ahrar Al Sham, fought soldiers around the Taftanaz airbase in the north-west province of Idlib, the Syrian Observatory for Human Rights said. The Britain-based group said rebels stormed parts of the airbase before withdrawing.
The state-run Sana news agency said government forces protecting the base had "repelled the terrorists' attempt to attack the airport" and inflicted heavy losses.
The rebel Idlib Coordination Committee said opposition forces detonated a car bomb inside the base.
Rami Abdul Rahman, the head of the Observatory, said up to 800 fighters took part in the assault, including Islamists from Jabhat Al Nusra, a powerful group that the United States considers terrorists.
Taftanaz is mainly a helicopter base, used for missions to resupply army positions in the north, many of which are cut off by road because of rebel gains, and for dropping crude "barrel bombs" of explosives on rebel-controlled areas.
The rebels have been pursuing a strategy of attacking airports and military airfields, targeting five airbases in Idlib and Aleppo, trying to chip away at the government's air power.
Yesterday, the head of Lebanon's Hizbollah movement, Hassan Nasrallah, said Syria was threatened by "schemes of division and partition". "We fundamentally and ideologically reject any form of partition or division of any Arab or Islamic country and call for them to preserve their unity," said Mr Nasrallah, whose Shiite group is a long-time ally of Mr Al Assad's regime.
* Reuters, Agence France-Presse