Civilians fleeing Syria's war will not be allowed to enter Israel, Prime Minister Benjamin Netanyahu said on Sunday adding however that his government will continue providing them with humanitarian aid.
Jordan on Sunday mediated a new round of talks between rebels and Assad's main ally Russian Federation, seeking a wider truce in the area to avert more bloodshed and another wave of displaced people near its border.
Israel's military says it deployed additional tank and artillery forces on the Syrian front on Sunday as a precaution given intensified fighting over the border between regime's forces and the opposition.
Losing Busra al-Sham, a major town near the provincial capital of Daraa, would be a significant loss for the opposition in the teeth of a Russian-backed Syrian army offensive in the southwest that has taken chunks of rebel territory.
The Syrian Observatory for Human Rights said on Monday that negotiations between the Russians and the representatives of towns in the eastern countryside of Daraa achieved great progress.
Retaking the whole of Daraa province would be a symbolic victory for the regime, as it is seen as the cradle of the anti-Assad uprising seven years ago that spiralled into civil war.
The massing refugees at the border aren't going to be allowed across, however. The northwestern chunk of Daraa province remains in opposition hands.
Tens of thousands of the more than 160,000 civilians who have been displaced, according to United Nations figures, have given up on entering Jordan and have instead headed westwards to the Israeli border.
The campaign has shattered a "de-escalation" deal negotiated by the United States, Russia and Jordan that had mostly contained fighting in the southwest since a year ago.
Jordan has been facilitating the talks to end the fighting, which has brought thousands of families seeking safety to its border.
Internally displaced people from Daraa province arrive near the Israeli-occupied Golan Heights in Quneitra, Syria, on Friday.
Both Jordan, which already hosts more than half a million Syrian refugees, and Israel, have said their borders will stay shut.
UN High Commissioner for Human Rights Zeid Raad Al Hussein warned that many civilians risk being trapped between government forces, rebels, and ISIS, which has a small foothold there - an outcome he said would be a "catastrophe". So far, about 100 civilians have been killed in air raids and shelling since June 19, it said.
The opposition's chief negotiator in wider U.N. peace talks, Nasr al-Hariri, last week accused the United States of complicity in Assad's southwest offensive, saying American silence could only be explained by "a malicious deal".
"Regarding southern Syria, we will continue to defend our borders".