Syrian regime forces have for weeks been preparing an offensive to retake rebel-held towns in southern part of the country.
Syrian regime forces pounded rebel-held parts of the southern city of Daraa with rockets and barrel bombs overnight causing dozens of families to flee, a monitor and an AFP reporter said on Monday.
Government forces have for ramped up their bombardment of the wider province of the same name for nearly a week, as fears rise of a full-blown regime assault to retake the country's south from rebels.
Regime helicopters dropped barrel bombs on rebel-held areas of Daraa city for the first time in a year, the Britain-based Syrian Observatory for Human Rights monitor said.
An AFP correspondent said the heavy bombardment pushed dozens of terrified families to flee their homes on foot or on the back of motorbikes to seek shelter in olive groves on the outskirts of the city.
Some families took refuge in small shelters or tents between the olive trees, the correspondent said.
Russian-backed regime forces have been preparing an offensive to oust rebels from Syria's south, a strategic area bordering Jordan and the Israeli-occupied Golan Heights.
President Bashar al Assad's forces have ramped up their bombardment of Daraa's eastern countryside since Tuesday and on the weekend ally Russia bombarded it for the first time in a year.
On Monday morning, Russian and regime aircraft continued to bomb villages and towns in the east, the Observatory said.
Regime forces launched barrel bombs on the town of Basr al Harir, while heavy shelling and rocket fire of the Al Laja area put a civil defence centre out of service.
The uptick in violence has killed at least 28 civilians in just under a week, the monitor said, with rescue teams struggling to reach affected areas due to the intensity of the bombing.
More than 17,000 civilians have also been displaced from their homes in Daraa's eastern countryside, the Observatory said.
The United Nations has warned that renewed hostilities could put 750,000 lives in rebel parts of Daraa at risk.
Parts of Daraa, as well as the neighbouring provinces of Quneitra and Sweida, fall under a "de-escalation zone" agreed by Russia, the US and Jordan in July 2017.
Since then, Russia whose warplanes have backed Assad's forces since 2015 had refrained from bombing the south of the country until it resumed strikes Saturday.
Daraa and the adjacent province of Quneitra are mostly held by opposition forces, while the regime controls most of the province of Sweida to the east.
More than 350,000 people have been killed in Syria's civil war and displaced millions since it started in 2011 with the brutal repression of anti-government protests.