The evacuation of fighters and civilians from devastated eastern Aleppo as well as emergency medical access for the area's sick and injured could be delayed up to 24 hours to Thursday (15 December) over demands by pro-government forces.

Four years of bloody stalemate in Aleppo, Syria's most populous city before the start of the civil war, ended yesterday (13 December) following a ceasefire brokered by Russia and Turkey. Russia and Iran have been the principal backers of the Bashir al-Assad regime in Damascus. Turkey, the gulf monarchies and the US and the UK have backed the country's rebels, now defeated in Aleppo.

The ceasefire had been agreed to on the condition evacuations from areas of Aleppo previously held by the rebels would begin at 5am local time (3am BST). However, as dawn broke in the battered eastern districts, none of the government's buses had departed to take residents to their destinations in rebel held areas.

A total of twenty buses were waiting there with their engines running at an agreed upon point but showed no sign of moving into Aleppo's rebel-held eastern districts, Reuters reported. Ambulances approaching the besieged areas have also been turned back

Rebels still in eastern Aleppo have blamed the delay on Iran. "What is stopping the agreement presently is Iranian obstinacy. But the deal still stands, the ceasefire stands until now," a commander with the Nour al-Din al-Zinki group said.

The BBC reported it had become an established tactic by the pro-Assad forces to secure the evacuation of its own fighters from rebel besieged towns following victories and agreed local ceasefires.

As the ceasefire was announced, it was agreed those leaving would be allowed to travel to other rebel-held territory in the west of Aleppo province or neighbouring Idlib province.

A bus driver waits to evacuate people from a rebel pocket in Aleppo
A bus driver waits to evacuate people from a rebel pocket in Aleppo, in the government-controlled al-Hamadaniah Stadium of Aleppo, Reuters

The deal was announced hours after UN agencies reported that pro-government forces had been summarily killing civilians in Aleppo, including women and children.

Unicef added that as many as 100 children may be trapped inside a building under heavy attack in the city.

Parts of Aleppo were seized by rebel groups after the 2011 uprising against the regime of President Bashar al-Assad.

In recent months, pro-government forces launched a major offensive to regain control of the city, with Russia's military saying 98% of territory was back in government hands.