Intense clashes took place in Damascus early on Monday as the army counter-attacked rebels who had advanced in the northeast of the Syrian capital on Sunday, a war monitor said.
A Syrian military source said on Monday that the army had recaptured all the positions it had lost on Sunday.
A Reuters witness said that warplanes were active above Damascus early in the day and that some streets in government-held areas near the fighting had been closed.
The Syrian Observatory for Human Rights, a British-based war monitor that collects information from a network of sources across Syria, said heavy fighting continued around the Jobar and al-Qaboun districts in the northeast of the city.
Rebels had attacked in Jobar to relieve military pressure after their recent loss of ground in nearby Qaboun and Barza, a commander from the Failaq al-Rahman group which is fighting there said on Sunday.
Syrian President Bashar al-Assad and his army, along with allied Russian, Iranian and Shi'ite militia forces, have put rebels on the back foot with a steady succession of military victories over the past 18 months, including around Damascus.
Rebels still hold a large, heavily populated enclave in the Eastern Ghouta district of farms and towns to the east of the capital, as well as some Damascus districts in the south, east and northeast of the city.
The most recent fighting has focused on the areas around Qaboun and Barza, which the army has isolated from the rest of the main rebel enclave of Eastern Ghouta and the eastern districts of Damascus.
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