BEIRUT: Civilians and opposition fighters will start evacuating east Aleppo `within hours` under a deal with Syria`s regime, a rebel official said on Tuesday, as global outrage mounted over reports of atrocities including summary executions.

Yasser al-Youssef from the political office of the key Nurredin alZinki group said the deal with President Bashar al-Assad`s regime was being `sponsored` by Russia and Turkey.

`An agreement has been reached,` Youssef said. `The first stage will be the evacuation of civilians and wounded, within hours, and afterwards fighters will leave with their light weapons.` Those leaving will be allowed to travel to other rebel-held territory in the west of Aleppo province or neighbouring Idlib province, he said.

A source in the powerful Ahraral-Sham rebel group confirmed the deal and its details. There was no immediate confirmation from the regime, Ankara or Moscow.

The United Nations and aid agencies have been pleading for a ceasefire to allow for the evacuation of tens of thousands of civilians trapped in the last pocket of rebel territory in Aleppo.

After weeks of heavy fighting, forces loyal to Assad were in the last hours of a push to take full control of the city, dealing the biggest blow to Syria`s rebellion in more than five years of civil war.

Butas thelongbattle reachedits final stages, the United Nations said it had received reports of at least 82 civilians, including 11 women and 13 children, being executed by pro-government forces.

Following a request from Britain and France,theUNSecurity Council was to hold an emergency meetingto address what the French envoy called `the worst humanitarian tragedy of the 21st century unfolding before our eyes` Speaking to reporters in Geneva, UN rights office spokesman Rupert Colville said it had received credible reports of the civilian executions in recent days.

Pro-government fighters had in some cases entered homes and killed those inside, and in others `caught and killed on the spot` fleeing civilians, he said.

The UN was `filled with the deepest foreboding for those who remain in this last hellish corner of opposition-held eastern Aleppo` Colville said. Residents in remaining rebel-held territory said they had no hope lef t.

`Our fate is sealed. Why would we hide, it won`t do us any good.

We will either die or be captured, said Ibrahim Abu al-Leith, aspokesman for the White Helmets rescue service.

Other witnesses described scenes of carnage in rebel areas, with bodies lying amid the rubble of city streets, as desperate residents sat on pavements with nowhere to shelter.

French Foreign Minister JeanMarc Ayrault said there were worrying reports of `cold-blooded killings of entire families`, `summary executions, including of women and children` and `people burned alive in their homes`.

`Such atrocities are unconscionable. Supporters of the regime, starting with Russia, cannot let this happen.` Britain repeated its call for Assad to step aside, citing his `barbaric cruelty`, and French Prime Minister Bernard Cazeneuve said `massacres` in Aleppo could amount to war crimes and crimes against humanity.-AFP