Jordan's mediation has allowed talks on a peace deal in the rebel-held town of Deraa in south-western Syria to resume between the Syrian opposition and Russian officers.
Talks came to a halt on Saturday after the rebels rejected a demand to surrender by Russia — which backs Syrian President Bashar Al Assad.
A string of Syrian rebel-held towns and villages were forced to accept government rule on Saturday as insurgent lines collapsed in parts of the south-west under intense bombardment.
A team representing the Free Syrian Army (FSA) rebels was holding talks with Russian negotiators in the town of Busra Al Sham, a spokesman for the central operations room representing FSA negotiators told Reuters.
"The talks have resumed this morning between the Russian side and the opposition in southern Syria under Jordanian auspices," Ibrahim Al Jabawi said.
Jordanian Foreign Minister Ayman Safadi said the kingdom was engaged in intensive diplomacy with all parties in the conflict to help broker a ceasefire that would ease plight of displaced civilians.
"We are moving in all directions and with all the parties to bring a ceasefire and protect civilians," he said in a Tweet on Saturday.
Jordan began delivering aid to the tens of thousand of civilians who have fled to areas near across the border since the Syrian government offensive in Deraa began on June 19. Thousands of others have sought safety along the border with the Israel-occupied Golan Heights.
More than 100 civilians have been killed and about 160,000 forced to flee their homes, according to a war monitor and the United Nations.
The campaign, backed by Russian air strikes, has put more than half the province under government control, compared with just 30 per cent earlier, according to the Syrian Observatory for Human Rights.
Meanwhile, Israel said it deployed additional tank and artillery forces near the Syrian border on Sunday as a precaution amid intensified fighting there between Syrian regime troops and rebels.
Prime Minister Benjamin Netanyahu said Israel would not allow civilians fleeing the fighting to enter the country, but would provide them with humanitarian aid.
"Regarding southern Syria, we will continue to defend our borders," Mr Netanyahu said at the start of a cabinet meeting on Sunday. "We will extend humanitarian assistance to the extent of our abilities. We will not allow entry into our territory."
The Assad troops' assault has so far focused on Deraa, not rebel-held parts of nearby Quneitra province in the Golan Heights which are more sensitive to Israel.
"The forces deployed this morning as part of preparations and readiness in light of developments on the Syrian Golan Heights," the military said on Twitter. It added that Israel was holding to a policy of non-intervention in Syria's civil war.
Talks to end south Syria military campaign collapse
Pope Francis decried the intensified attacks in southern Syria in remarks at the Vatican on Sunday, asking that people there be spared more suffering.
The pope lamented that "the military actions of recent days have struck even schools and hospitals and triggered thousands of new refugees".
He renewed his appeal for peace so that Syrians, could be "spared further suffering" after more than seven years of war.
Also on Sunday, Russia's military said that it shot down unidentified drones near Russian Hmeimim airbase in Syria, RIA news agency reported.
The report added that the base was not damaged during the incident.