Syrian rebels on Saturday blocked army reinforcements advancing towards the strategic town of Maaret al-Numan which has been under rebel control, an AFP journalist said.
In its bid to retake the town, located in northwest Syria on the road from Damascus to the embattled city of Aleppo, the army used warplanes to bombard Maaret al-Numan, killing at least two civilians and destroying three homes.
Some 40 military vehicles, including 10 tanks, four-wheel-drive vehicles with mounted machineguns and buses loaded with troops were forced to stop 10 kilometres (six miles) south of the town, rebel fighters told AFP.
The rebel Free Syrian Army used anti-tank rockets and improvised explosives to block the army's progress.
The FSA seized control of Maaret al-Numan on Tuesday, pushing the army out into two military bases on its outskirts, and blocking the arrival of new reinforcements to Aleppo.
"The rebels tried again to storm the Wadi Deif army base (on Saturday) ... when they were bombarded by a MiG fighter jet," said Syrian Observatory for Human Rights director Rami Abdel Rahman.
Fierce machinegun battles raged near the base.
Regime forces have been launching rockets daily from the two bases on the outskirts, focusing their fire mainly around an underground emergency field hospital.
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On Saturday, army shelling injured 20 rebel fighters, the Observatory said.
Some 125,000 people once lived in Maaret al-Numan and its outskirts but most have fled because of the violence. Alongside the rebels, only a few elderly men remain in the town, guarding homes and shops.
Rebel fighters decorate their motorbikes and the few cars they have with the colours of the Syrian independence flag, which has come to symbolise the revolt against President Bashar al-Assad's regime.
Experts say the Syrian army has been worn down by an increase in the number of battlefronts and rebel attacks that have cut major supply routes and undermined the regime's military superiority.
The army relies mainly on its monopoly on air power to slow the progress of the insurgency.
"The army can try and take back the town from rebel hands temporarily, but it's clear that it can no longer keep control of it," said the Observatory's Abdel Rahman. "The army is genuinely losing control in the north."
Rebels staged a massive assault on Aleppo, Syria's traditional commercial hub, on July 20, after they had slowly built up a strong presence in the countryside of Idlib and Aleppo, both neighbouring Turkey.
Both the army and rebels have since kept up a continuous flow of reinforcements into Aleppo city, as they bid to take full control.
"There are thousands of rebel fighters all across the northern belt of Syria, mainly in Idlib and Aleppo, and the army has been unable to do much about that," said Abdel Rahman.