Fresh battles broke out in a flashpoint district of Aleppo on Monday, while violence raged on the road linking the Syrian city to its international airport, a watchdog said.
"Fierce clashes raged between troops and rebels in the east of Sheikh Maqsud district," said the Syrian Observatory for Human Rights, a day after a major rebel advance in the predominantly Kurdish neighbourhood.
Regime tanks fired shells at other parts of the neighbourhood, whose residents fled the area in large numbers for a second straight day.
Southeast of Aleppo, fresh clashes broke out near the city's international airport, said the Observatory, which relies on a network of activists, doctors and lawyers across Syria for its reports.
The airport has been closed since January.
Aleppo city has been scene of some of Syria's fiercest violence since battles first broke out in the northern city in July last year.
Much of the city has since been destroyed, and residents suffer constant power cuts and frequent water shortages.
To the west of the city, an air strike on rebel-held the town of Maaret al-Numan killed at least one child, said the Observatory, which reported several others injured.
Located in the northwestern province of Idlib, Maaret al-Numan has been under rebel control since October last year.
Elsewhere, a blast caused by an explosive device hit the Rokn Eddin district in northern Damascus, said the Observatory, which also reported renewed shelling by government troops on rebel-held districts in the central city of Homs.
Monday's violence comes a day after at least 181 people were killed across Syria, among them 57 rebels, 67 civilians and 57 loyalist troops, the Observatory reported.
The UN says more than 70,000 people have been killed in Syria's two-year war.