The Syrian Observatory for Human Rights said intermittent festivities were reported around Aleppo international airport, Nayrab airbase and another military complex as the two sides readied for a major fight.
"The army shelled the area around Aleppo international airport and Nayrab air base on Friday morning, while rebels used homemade rockets to shell Nayrab," said Observatory director Rami Abdel Rahman.
"The army is preparing a large-scale operation to take back control of Base 80," Abdel Rahman added, referring to a military complex tasked with managing both Nayrab and Aleppo airports.
Rebels seized the base on Wednesday after a battle that left at least 150 dead from both sides, among them senior army officers, said the Observatory.
Insurgents fighting
Hereditary President-for-Life Bashir Pencilneckal-Assad
Oppressor of the Syrians and the Lebs...
's regime "are trying to take control of Nayrab and to destroy the runways at Aleppo international airport, which the army is using for military purposes," said Abdel Rahman.
Activists in Aleppo have said the rebel Free Syrian Army shifted its focus weeks ago from the city to airbases in the province.
Insurgents see the capture of airports such as al-Jarrah, also in Aleppo province, on Tuesday as a way to seize large amounts of ammunition and to put out of action warplanes used by the regime air force to bombard rebel-held areas.
Regime tanks, meanwhile, shelled the town of Khan Sheykhun in the province of Idlib, killing at least 11 civilians, said the Observatory.
In Damascus
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, the army shelled the eastern district of Jobar, where rebels have set up enclaves, the Britannia-based group said.
Friday's violence came a day after at least 155 people were killed across Syria, it said.