More than a quarter of a million people have fled their homes because of President Bashar Al Assad's onslaught of south-western Syria in the past fortnight, the UN said on Monday, prompting calls by Jordan for a ceasefire.
The rising numbers – more than 270,000 according to the UN – were met with alarm in Jordan, where the government has said it cannot accept any more refugees.
Jordanian Foreign Minister Ayman Safadi will travel to Moscow on Tuesday to meet with Russia's top diplomat Sergei Lavrov over the crisis, the latest human exodus caused by the more than seven year war.
"I look forward to a frank discussion to discuss how to arrive at a ceasefire as soon as possible," Mr Safadi said in Amman, adding that he would also be seeking ways to alleviate a worsening humanitarian situation.
The Russian government has backed the Syrian regime’s heavy military campaign to recover the area.
Rebels in southern Syria were divided on Monday over whether to accept deals offered by Russia that would see regime forces retake control of opposition towns.
After talks with Moscow, a number of rebel groups agreed in recent days to a government takeover in exchange for an end to the ferocious air strikes and barrel bombing.
With those capitulations, regime forces have doubled their territorial control in the main southern province of Deraa to about 60 per cent since operations began on June 19.
But other opposition bodies have rejected the deals, while the numbers of those leaving the area continues to rise.
"Our latest update shows the figure of displaced across southern Syria has exceeded 270,000 people,” said Mohammed Hawari, a UN refugee spokesman in Jordan, noting that the number had been expected to peak at 200,000. "We're facing a real humanitarian crisis in southern Syria," he added.
A week ago the international organisation said that 160,000 people had been displaced.
The strategic area was ostensibly protected by a ceasefire agreed by the US, Jordan, and Russia just under a year ago, but President Al Assad is dead-set on retaking it.
The violence has pushed waves of terrified civilians out of their homes at a shocking rate, the UN said.
Most of those escaping the fighting have fled to the borders with Jordan and the Israeli-occupied Golan Heights.
According to the UN, Jordan hosts about 650,000 registered Syrian refugees and has said that it will not open its border for more to cross. Israel has also said that it will not let in any refugees.
The UN has warned of a humanitarian catastrophe in the southwest caused by the fighting.
Following his meeting with UN officials on Monday, Mr Safadi said that shipments of aid were waiting to get approval to enter Syria from the Jordanian border.
In a statement on Monday, the civilian half of the Syrian opposition's delegation to hold talks with Russia said they withdrew.
"We did not attend negotiations today. We were not party to any agreement and we never will be," said the statement, signed by negotiator Adnan Musalima.
It accused some actors of trying to secure personal interests through the agreements.
The Britain-based Syrian Observatory for Human Rights said on Monday there were "divisions among rebel groups" over whether to agree to the terms proposed by Russia.
Under the deal offered, rebels would hand over medium and heavy weapons and Syrian state institutions would resume work. Displaced families could return with guarantees by Russian military police.
Men who defected from Syria's armed forces or who did not complete their compulsory service could regularise their status with the regime within six months.
And regime forces would take over the Nasib border crossing with Jordan as well as deploy along the frontier with the Israeli-occupied Golan Heights, Observatory head Rami Abdel Rahman said.