Syrian rebels attacked a military airport in the country's north on Saturday in a push to cut off Syria's biggest city Aleppo from the capital Damascus, and secure a strategic north-south corridor.

President Bashar al-Assad's forces appear over-stretched with fewer fighters on the ground and have sought to limit rebel advances with far superior firepower, increasingly from the air and especially in the Aleppo and Damascus areas.

But despite ragged command-and-control and few heavy weapons, the rebels have gained control over the rural north and border crossings to Turkey after 19 months of conflict and now seek to isolate Aleppo from Assad's power fulcrum in Damascus.

Abroad, fragmented anti-Assad opposition groups will try again at a meeting in Qatar starting on Sunday to form a united front in pursuit of international respect and, most important, better weapons to turn the battlefield tables and oust Assad.

Fighters from the Islamist Front to Liberate Syria said they launched the attack on the Taftanaz military airport in the northern province of Idlib in the early hours on Saturday, using rocket launchers and at least three tanks.

The government has used Taftanaz to fuel helicopter gunships and fighter jets that have bombarded nearby villages.

"All planes that bomb Idlib take off from that airport, and also, if we liberate it, the road between Aleppo and Idlib will be open and safe," a rebel from the Sukour al-Sham brigade said.

"We have managed to destroy one helicopter and several anti-aircraft batteries, and we are using tanks to shell the base," he told Reuters by phone from the scene.

Syrian warplanes attacked the nearby village of Bennish in retaliation, the Britain-based Syrian Observatory for Human Rights said.

Further fighting was reported in the eastern, oil-producing province of Deir al-Zor and on the outskirts of Damascus.

The revolt against Assad began as peaceful rallies calling for more freedoms and democracy but turned to armed struggle against the military machine that he unleashed on protesters.

Diplomatic intervention has been fruitless because major world and regional powers are at loggerheads over how to end the conflict. It has killed about 32,000 people, making it the bloodiest of Arab uprisings that have ousted entrenched leaders in Tunisia, Egypt, Libya and Yemen since early last year.-Reuters