Heavy clashes rocked eastern districts of the Syrian capital on Sunday as rebels and jihadists tried to fight their way into the city centre in a surprise assault on government forces, reports AFP.
The attack comes just days before a fresh round of UN-brokered peace talks in Geneva aiming at ending Syria's six-year war.
Rebels and government forces agreed to a nationwide cessation of hostilities in December, but fighting has continued across much of the country, including in the capital.
Steady shelling and sniper fire could be heard across Damascus as rebel factions allied with former Al-Qaeda affiliate Fateh al-Sham Front attacked regime positions in the city's east.
The attack began "with two car bombs and several suicide attackers" in the Jobar district, said Rami Abdel Rahman, head of the Syrian Observatory for Human Rights monitoring group.
Rebels seized several buildings in Jobar and advanced into the nearby Abbasid Square area, seizing part of a bus station before being pushed back, he said.
"After a major advance by opposition fighters, the regime got over its shock and began a counter-offensive," he said.
State television, quoting a military source, said the army "tightened the noose around terrorist groups besieged in the industrial zone on the northern edges of Jobar".