[BBC] – A deal to evacuate rebel fighters and civilians from eastern Aleppo has stalled, with heavy shelling reported in the Syrian city.

A ceasefire was declared in Aleppo on Tuesday and buses brought in to ferry people out of the devastated enclave.

But fighting resumed on Wednesday. Syrian activists also say air strikes over rebel-held territory have resumed.

The breakdown of the deal, brokered by Russia and Turkey, is being attributed to demands from the government side.

It is said to be seeking the evacuation of injured fighters and civilians from nearby towns encircled by opposition forces.

The latest on the ground

Eastern Aleppo has been held by the rebels since 2012. But they have been squeezed into ever-smaller areas in recent months by a major government offensive, backed by Russian air power.

In recent days government troops have made sweeping gains. Russia’s military said on Wednesday that rebels were confined to only 2.5sq km of the city.

Late on Tuesday, Russian UN Ambassador Vitaly Churkin told an emergency session of the UN Security Council that “military actions in eastern Aleppo are over”.

Under the evacuation deal, civilians and rebels from eastern Aleppo were to be allowed to go to rebel-held areas in northern Syria.

Evacuations had been due to start at 05:00 (03:00 GMT), but did not go ahead. Fresh shelling was reported several hours later.

“The clashes are violent and bombardment is very heavy… it seems as though everything (the ceasefire) is finished,” Rami Abdulrahman, director of the British-based Syrian Observatory for Human Rights (SOHR) monitoring group, said.

The SOHR also said aircraft had resumed bombing in rebel-held areas.

Russia – Syria’s ally – said the Syrian army resumed firing after the rebels broke the truce. Syrian TV reported rebel rocket fire on government-held parts of the city and said at least six people had been killed.

Turkish President Recep Tayyip Erdogan accused Syrian forces of breaking the ceasefire deal and called the situation in Aleppo “very fragile”. He said civilians had to be allowed to leave.

Residents of besieged eastern Aleppo have faced weeks of bombardment and chronic food and fuel shortages. Medical facilities in the city have largely been reduced to rubble.

AFP news agency reported that before the fighting had resumed, crowds of civilians, holding belongings, had gathered in the streets to await evacuation.

Residents say they fear reprisals from government forces or being forcibly conscripted. There have also been reports of atrocities.

On Tuesday the UN said it had received reliable evidence of summary executions taking place, saying that in four areas 82 civilians were killed by pro-government forces. It said that many more may have died.

Syria’s government and Russia said the allegations were untrue.

It is not clear exactly how many people remain in Aleppo’s besieged areas. UN envoy Staffan de Mistura put the figure at about 50,000.

He said there were approximately 1,500 rebel fighters, about 30% of whom were from the jihadist group formerly known as the al-Nusra Front.

Other local sources say there could be as many as 100,000 people, many of them arriving from areas recently taken by the government.