Waves of air strikes pounded rebel-held areas of southern Syria on Thursday as pro-regime forces launched heaviest bombing campaign in a two-week-old offensive.
The attack came after Russian-brokered talks to end the offensive in Daraa province failed Wednesday.
An AFP correspondent on the edge of the rebel-held south of the city of Daraa, the divided provincial capital, said the bombing of rebel neighbourhoods was the most intensive since the launch of the Russian-backed offensive on June 19.
Hundreds of missiles and crude barrel bombs were unleashed by Syrian and Russian aircraft overnight, according to The Syrian Observatory for Human Right.
Observatory director Rami Abdel Rahman said the bombardment was an "attempt to make the rebels back down after they refused to subject themselves to the Russian terms for a ceasefire."
"Air strikes were ongoing, including on the town of Tafas in the northwest of Daraa province and on towns and villages near the Jordanian border," the Observatory added.
AFP reported that the talks this week aimed at keeping rebel territory in Daraa province's western countryside and the southern half of the provincial capital.
Following a meeting with a Russian delegation on Wednesday afternoon, a joint rebel command for the south said talks had failed over the issue of the rebels surrendering their heavy weapons.
Nearly 150 civilians have died since the assault began, according to the Observatory.
