Russia claims the Syrian army has suspended combat operations in Aleppo to allow for the evacuation of civilians from besieged rebel-held neighbourhoods - but residents and fighters are reporting no let-up in the bombing and shelling campaign.
Russian foreign minister Sergey Lavrov, speaking in Germany after talks with US Secretary of State John Kerry, said military experts and diplomats would meet in Geneva on Saturday to work out details of the rebels' exit from Aleppo's eastern neighbourhoods, along with civilians who were willing to leave the city.
Mr Lavrov said the Syrian army suspended combat action late on Thursday to allow some 8,000 civilians to leave the city in a convoy spreading across a five-kilometre route.
However, opposition activists said there was no halt to the government offensive.
"Battles are intense," said a message from a rebel operation room shared with The Associated Press.
Other residents reported warplanes firing from machine guns at rebel positions and artillery shells falling in the remaining rebel-controlled districts.
In Washington, State Department spokeswoman Elizabeth Trudeau said the US was focused on de-escalating the violence in Aleppo to allow aid into the city and enable people wishing to stay in their homes to do so.
She said Mr Kerry and Mr Lavrov continued talks on Thursday with the goal of securing a cease-fire and the "safe departure of those who wish to leave the city".
She said details of Saturday's US-Russian technical discussions in Geneva were still being worked out.
Earlier, in Geneva, UN special adviser Jan Egeland said efforts to evacuate hundreds of wounded people from eastern Aleppo had stalled following a deadly attack this week on a Russian military hospital in government-controlled western Aleppo that left two Russian nurses dead and a doctor seriously wounded.
"It is with bitterness and frustration that we have to report that we have not been able even to evacuate the wounded," Mr Egeland said.
"The member states that are supposed to help us get access to civilians in the cross-fire are poles apart in how they regard what is happening in Syria."
He said Syrian president Bashar Assad's government had authorised UN-organised aid shipments into eastern Aleppo for the first time.
However, he provided no details about how the aid might get in or where it would go, and past agreements have fallen through before any aid could be delivered.
Medical officials in the enclave issued a passionate plea for a ceasefire.
"Aleppo is finished. There is nothing left except a few residents and bricks," Mohammed Abu Jaafar, the head of the eastern Aleppo forensic authority, said in a recorded message shared with reporters. "This may be my last call."
By early afternoon, Mr Abu Jaafar said 14 bodies had arrived at his facility from all over eastern Aleppo, although a comprehensive death toll for the day was not possible because of the intense fighting.
Residents described streets littered with bodies as ambulances and rescue workers struggled to keep up.
The rebel defences have buckled amid the wide-ranging government offensive, which opened a number of fronts at once and was preceded by an intensive aerial campaign.
More than three-quarters of the rebel sector has now fallen, including the symbolically important ancient Aleppo quarters. More than 30,000 of the estimated 275,000 residents of the besieged eastern enclave have fled to western Aleppo.
The Syrian government has dismissed a proposal for a ceasefire put forward by the rebels on Wednesday.
In comments published on Thursday in the state-owned al-Watan newspaper, Mr Assad said he would no longer consider truce offers, adding that such proposals, particularly by the Americans, often come when the rebels are in a "difficult spot".
"That is why we hear wailing and screaming and pleas for truces as the only political discourse now," Mr Assad said.
He said that while a victory by Syrian government forces in the battle for Aleppo would be a "big gain", it will not end the country's civil war.
"Liberating Aleppo from the terrorists deals a blow to the whole foundation of this project," he said. But he added, "to be realistic, it doesn't mean the end of the war".
On Thursday, opposition activists reported intensive bombing in the al-Sukkari and Kallaseh neighbourhoods still under rebel control.
Al-Sukkari is in the southern part of eastern Aleppo, an area that has become home to the majority of the displaced civilians who stayed behind; Kallaseh is near the Old City.
Footage by the Syrian military showed intensive shelling of Bustan al-Qasr, a frontline neighbourhood that links the rebel-held eastern and government-controlled western parts of the divided city.
The International Committee for the Red Cross said that it had evacuated 148 disabled civilians and others in need of urgent care from a facility in Aleppo's Old City after fighting calmed down there.
The evacuation, undertaken jointly with the Syrian Arab Red Crescent, was completed late on Wednesday, the Red Cross said in a statement.
The people had been trapped in a facility that was originally a home for the elderly and included mentally and physically disabled patients, as well as injured civilians who had sought refuge there.
"They were forgotten," said Pawel Krzysiek, the agency's communication co-ordinator in Damascus.
The evacuees were taken to a hospital and shelters in the western, government-held part of Aleppo.