Backed by Russian air strikes the Syrian army is gaining more ground in rebel held eastern province of Deraa.
Two weeks into a bloody offensive it's now in control of about 60 percent of the region.
Deraa was the birthplace of the Syrian revolution and is also diplomatically sensitive because it borders Lebanon, Jordan and Israel.
It's remained under opposition control since the start of the war.
On Tuesday Syrian rebel negotiators began a new round of talks with Russian officers over a peace deal in southern Syria under which they would hand over weapons and allow Russian military police to enter rebel-held towns, a rebel spokesman said.
Spokesman Ibrahim al Jabawi said the rebels had carried to the negotiating table their "response to a list of Russian demands" that include the handing over of weapons and settling the status of rebels in a deal that ends the fighting.
The Russian demands, handed to rebels in a meeting in a town in southern Syria on Saturday, had prompted a walkout by the rebels, who said the terms amounted to a humiliating surrender.
The opposition team was then persuaded by Jordan to go back to the negotiating table, diplomatic sources said.
Jordan has been working behind the scenes to spare more bloodshed and destruction to a region whose future stability is crucial to the kingdom's own security.
The arrival of thousands of uprooted Syrians among the tens of thousands near Jordan's border has created new security challenges and a humanitarian nightmare for the authorities.
Syria's multi-sided conflict has uprooted nearly 11 million people, including 6 million who fled abroad in one of the worst refugee crises of modern times.