Gunmen on Thursday killed eight Syrian regime fighters and captured 15 others during the fiercest clashes in the southern province of Daraa since it came under government control, a war monitor reported.
Russian-backed Syrian army and allied forces recaptured Daraa from rebels in 2018, a symbolic blow to the anti-government uprising born there in 2011.
State institutions have returned, but the army still hasn't deployed across the whole province, and tit-for-tat bombings and assassinations between former opposition figures and regime forces have since become routine.
Tensions flared on Thursday, leading to what the Syrian Observatory for Human Rights called the "most violent and broadest clashes in Daraa since it came under regime control".
Fighting started when regime forces fired artillery shells towards the former opposition hub of Daraa 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 Daraa instead of evacuating under a Moscow-brokered deal, either joining the army or remaining in control of parts of the province.
Daraa al-Balad, a southern district of Daraa city, is among the areas controlled by former opposition forces.
In response to Thursday's shelling, gunmen launched a counterattack across many parts of Daraa's countryside, where they captured several regime positions.
"Eight Syrian regime and allied militia fighters died during clashes across Daraa province in recent hours," the Observatory said.
"Gunmen also captured more than 15 members of the regime forces in Daraa's western and eastern countrysides," it said.
The war in Syria has killed nearly 500,000 people and displaced millions since it started in 2011.