Military has stepped up bombing of rebel-held northwest since President al-Assad was sworn in for a new term last week.
Fighting between Syrian government forces and rebels has intensified near Deraa city, in what has been described as the heaviest clashes since the southern eponymous province came under government control.
Tensions flared on Thursday, leading to what the Syrian Observatory for Human Rights called the “most violent and broadest clashes in Daraa [Deraa] since it came under regime control”.
The fighting started when government forces fired artillery shells towards the former opposition hub of Deraa al-Balad in tandem with a ground push, the Britain-based war monitor said.
The pro-government Al-Watan newspaper called it the “start of a military operation against hideouts of terrorists who thwarted a reconciliation deal”.
Many former rebels stayed in Deraa instead of evacuating under a Moscow-brokered deal, either joining the army or remaining in control of parts of the province.
Deraa al-Balad, a southern district of Deraa city, is among the areas controlled by former opposition forces.
According to local sources, the regime forces carried out the operation to strengthen their dominance in the Daraa al-Balad neighborhood, but failed.
Encountering residents and armed opposition groups, the regime forces had to withdraw after intense clashes.
After the regime forces attacked the neighbourhood with tanks and artillery shells, the clashes spread to the western and eastern countryside of Deraa.
The opposition forces managed to take control of 18 government military checkpoints there, the Observatory said.
The regime forces then targeted the settlements with mortar and artillery attacks.
The clashes resulted in the death of seven opposition fighters, the Observatory said, while at least eight members of the government forces and allied paramilitaries were killed.
The watchdog added that the opposition managed “to capture at least 40 regime forces and militias loyal it” during the fighting.
Scores of civilians killed
Mazen Albalkhi, a member of the Freedom for Deraa Campaign told Al Jazeera that Syrian and Iranian forces are indiscriminately targeting civilians.
“The people of Deraa have been living under siege since 35 days ago and around 55,000 civilians are still living under siege, forced by the Iranian forces backed by regime militias,” Albalkhi said.
“We are talking about 11,000 families – 12,000 of them women and children. The continuing and indiscriminate shelling is targeting civilians. 18 civilians have been killed from the early morning until this moment.”
Al Jazeera’s Resul Serdar reporting from Istanbul in neighbouring Turkey said rebel forces and residents of Deraa were trying to block roads and burned car tires “to stop the regime from advancing into the city.
“The heavy clashes are still going on but so far it seems that the massive attack from the regime has been repelled for now,” Serdar said.
Russian-backed government troops and allied forces recaptured Deraa from rebels in 2018, a symbolic blow to the uprising against President Bashar al-Assad that was born there in 2011.
State institutions have since returned, but the army has still not deployed across the whole province. Tit-for-tat bombings and assassinations between former opposition figures and government forces have since become routine.
Deraa al-Balad was blockaded by the regime forces on June 25 after residents, including former members of the Syrian opposition, resisted an order to surrender their light weapons and allow regime forces to search houses in the area.
According to the Deraa-based Reconciliation Center and local figures, the order was opposed because it violated the terms of a 2018 deal, under which the area residents and ex-opposition members had to surrender all heavy weapons.
The deal allowed thousands of rebels and civilians safe passage to other opposition-held regions, while Russia-backed regime forces launched an attack to reclaim Deraa.
The regime began its military action despite agreeing earlier this week to lift the blockade.