Troops backed by fighters from Lebanese Shiite militant group Hezbollah had recaptured large parts of Base 80 outside Syria's main northern city in an assault yesterday morning.
But rebel fighters, among them Al-Qaeda loyalists, counter-attacked after dark, using Grad rockets against the army's tanks and recovering all of the lost ground, the Syrian Observatory for Human Rights said.
"As a result of the fighting, the rebels and jihadists have retaken the parts of the base that were captured during the day by the army," the watchdog's director Rami Abdel Rahman said.
The rebels seized Base 80, which provided the garrison for both Aleppo international airport and the adjacent Nayrab military airfield, in February.
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They failed to capture either airport but civilian flights have been suspended since the start of the year because of rebel fire.
The army has made several advances east of of Aleppo in recent days, including the recapture of Sfeira, a town that had been under rebel control for a year.
More than 120,000 people have been killed in Syria since the conflict erupted in March 2011, according to the Observatory's figures.