The UN peace envoy for Syria on Friday proposed a plan for Al-Qaeda-linked fighters in Syria's Idlib province to pull back from cities and other civilian-populated areas to avert a bloodbath in the rebel-held province.
The United Nations has warned of a humanitarian disaster if Syrian forces, backed by Russia and Iran, launch an all-out attack in Idlib, the last major rebel bastion.
Addressing the Security Council, Staffan de Mistura also called for evacuation corridors to be opened for civilians to voluntarily leave the war zone, under UN monitoring.
The council was meeting as Turkey clashed with Iran and Russia at a summit in Tehran on how to address the crisis in Idlib, an enclave in northwest Syria where three million people live.
De Mistura proposed that a deadline be set for all fighters -- in particular the Al-Qaeda-linked Nusra Front -- to retreat from populated areas and that no military attacks would be launched during the pullback.
"This would apply in particular for Al-Nusra, who should be notified by the guarantors, in particular Turkey, which still has the capacity to send messages," he said.
A Security Council diplomat, speaking on condition of anonymity, expressed skepticism, saying it was unclear where the fighters would go and whether Syria could be persuaded to halt military action. "There are challenges," he said.
- Legitimate target -
Russia told the council meeting that some 40 to 45 armed groups with up to 50,000 people were operating in Idlib. About 16,000 are fighting in the ranks of Al-Nusra and 11,300 others are members of hardline groups, said Russian Ambassador Vassily Nebenzia.
Syrian civilians are "worn out by extremist tyranny" in Idlib, said Nebenzia, adding that armed groups linked to Al-Qaeda remain "a legitimate target for liquidation."
Britain recalled that targeting civilians amounts to war crimes and warned that Syrian commanders and military units loyal to President Bashar al-Assad will be held accountable for any violations in Idlib.
"There are more babies in Idlib than there are terrorists," said British Ambassador Karen Pierce. "I think this should give those engaged in military action pause for thought."
US Ambassador Nikki Haley warned: "If Assad, Russia, and Iran continue, the consequences will be dire."
"Syria is once again at the edge of an abyss," said French Ambassador Francois Delattre.
De Mistura is to hold talks in Geneva next week with Russia, Iran and Turkey in Geneva, the three countries of the Astana process, a track of talks on Syria's war that has largely eclipsed the UN-led peace process.
More than 350,000 people have been killed in Syria's seven-year conflict.