Syrian rebels retook a strategic base in the northern Aleppo province on Saturday, as shelling killed at least 11 people in nearby Aleppo city, the Syrian Observatory for Human Rights said.
The group said rebels, including jihadists from two Al-Qaeda affiliates, launched a nighttime counterattack against regime forces, after they captured parts of the base on Friday.
Using Grad rockets against army tanks, they were able to regain control of the parts of the strategic Base 80 that they had lost during Friday fighting, Observatory director Rami Abdel Rahman said.
The clashes killed at least 53 people -- 33 rebels and 20 loyalists.
The rebels seized Base 80, which provided the garrison for both Aleppo international airport and the adjacent Nayrab military airfield, in February.
They failed to capture either airport, though they have seized the Minnigh and Jarrah military airports in the area.
Civilian flights from Aleppo International Airport have been suspended since the start of the year because of rebel fire.
The army has made several advances east of Aleppo in recent days, including the recapture of Sfeira, a town that had been under rebel control for a year.
In Aleppo city, meanwhile, the Observatory said shelling killed at least 11 people, including four children.
In the north-western Ashrafiyeh district, which is largely under regime control, five people, two of them children, were killed by mortar fire, the Observatory said.
State television also reported deaths in the area, saying six children had been killed and blaming "terrorists," its terms for opposition fighters.
In the northeast of the city, six civilians died, the Observatory said, including a woman, a six-month-old baby and a three-year-old.
More than 120,000 people have been killed in Syria since the conflict erupted in March 2011, according to the Observatory.
Millions more have been displaced inside Syria or have fled abroad.