The UN envoy for Syria cautioned against a "devastating" battle in south-west Syria as regime forces stepped up their week-long bombardment to retake the area as a regime air strike killed 17 civilians hiding in a shelter.
Staffan de Mistura briefed the United Nations Security Council on Wednesday evening on setting up a Syrian constitutional committee, which he said may be overtaken by the launch of a ground assault on the key southern area around Deraa near the borders with Jordan and the Israeli-occupied Golan Heights. The offensive comes despite an internationally brokered “de-escalation zone” that was agreed for the region last year.
“Let us be aware of what this would mean, if the south-west sees a full-scale battle to the end, it could be like eastern Aleppo and Eastern Ghouta combined together,” Mr de Mistura said.
After his comparison to two of the bloodiest campaigns of the seven-year war, he urged the Security Council to "not allow another battle of such magnitude".
A barrage of airstrikes on rebel-held areas on Thursday killed at least 17 civilians, including at least five children, hiding in an underground shelter. An activist with the opposition-operated Horan Free Media, who goes by the name Abu Mahmoud Hournai, said the rescuers were still pulling bodies from the shelter by early afternoon.
He put the death toll at 20, saying women and children were among the casualties. "They are still pulling people from under the rubble," Hourani said. "The situation on the ground is disastrous."
Dozens of air strikes identified as Russian killed 22 civilians, a monitor said, mostly in the town of Al-Mseifra where the hospital was hit forcing medics to close the site. It is the fifth hospital closed by the regime strikes in the past week.
Another five civilians were killed in other rebel-controlled areas of Daraa, the main province in southern Syria.
"This is the highest toll since the escalation began on June 19," said Britain-based Syrian Observatory for Human Rights head Rami Abdel Rahman, adding that it brought the overall civilian toll since then to 93.
The Syrian Civil Defence, a team of first responders, said that more than 150 air strikes targeted 12 towns and villages in eastern and western Deraa since dawn on Thursday, setting off a new wave of displacement.
Regime forces captured the town of al-Harak and a string of villages near the city of Deraa. "The goal for them is to split the western Deraa countryside from the city and the eastern Deraa countryside,” said Abu Shaima, a rebel spokesman.
"We can't even catch up to count the air strikes," said Abdallah Mahameed, a rebel official in Deraa. "The house is shaking around us."
Up until Tuesday, the United Nations had estimated that nearly 50,000 people were on the move in Deraa, fleeing the violence, most of them heading to villages near the Jordanian border.
Mr de Mistura also cautioned that such fighting could increase tensions across the region and risk compromising momentum in political talks to reach a lasting peace deal.
Moscow launched air strikes over the weekend to support forces aligned with President Bashar Al Assad, including Iran-backed militias. Russia, one of the backers of the de-escalation deal, said it was still committed to the agreement despite its air force carrying out strikes in the region.
The head of the Syrian opposition on Thursday blamed the regime's escalation on "US silence". Washington is another backer of the deal.
Naser Al Hariri, who heads the committee that represents the opposition at the UN, said "it's shameful that Washington allowed" the ceasefire to collapse without any efforts to salvage it.
Mr Al Hariri said that only a "malicious deal" could explain the lack of US presence.
Jonathan Cohen, US deputy permanent representative to the UN, said the predominant opposition force in the area was the Free Syrian Army, not terrorists, and not a permitted target designated by the UN.
"The unilateral operations underway by the Assad regime and Russia in south-west Syria represent a violation of the ceasefire arrangement reaffirmed by President Trump and President Putin," Mr Cohen said.
US Central Command head Gen Joseph Votel backed Mr Cohen's remarks by urging Moscow to commit to its ceasefire agreement.
"Our position is that there has been an agreement between the US president and Russian president," Gen Votel told reporters on Thursday.
Meanwhile, the UN's humanitarian adviser for Syria, Jan Egeland, warned on Thursday against the loss of aid access to the area.
Mr Egeland believes that the frontier with the Israel-controlled Golan Heights is "hermetically closed" as tens of thousands of civilians are fleeing from south-western Syria.
He said the battle in Deraa has led to the discontinuation of what had been an "extremely effective lifeline across the border" from Jordan in recent days.
Meanwhile, hundreds of Syrian refugees in Lebanon have started to go back home.
About 400 Syrians in the Lebanese border town of Arsal were making the crossing on Thursday, having requested permission from the Lebanese and Syrian governments.
The majority of those returning are farmers. The refugees gathered in the Wadi Hmeid area near Arsal, some in pickup trucks or on tractors, where a Lebanese security officer checked their IDs against a list before allowing them to cross the border.