UN envoy offers rebel pullback from Syria's Idlib

The United Nations has warned of a humanitarian disaster if Syrian forces, backed by Russia and Iran, launched an all-out attack in Idlib, the last major rebel bastion.

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, launched 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 is 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.