As government forces pressed an assault in the divided city, regime artillery fire killed at least 26 civilians in east Aleppo on Wednesday morning, the Syrian Observatory for Human Rights monitor said.
Civilians have poured out of the besieged rebel-held east, battered by air strikes and heavy artillery fire by advancing regime forces.
AFP's correspondent in a southeastern district described artillery shells "coming down like rain" on Wednesday.
After one mortar attack, the motionless body of a girl was left crumpled in the street, her arm severed and her head pierced by a sliver of shrapnel. Rescue volunteers carried her body away on a motorcycle.
Regime forces and allied fighters have seized a third of the rebel-held east of Aleppo since they began an operation to recapture all of the battered second city just over a fortnight ago.
They now fully control the city's northeast and pressed their offensive Wednesday on Aleppo's southeastern edges, advancing in the Sheikh Saeed district, according to state news agency SANA.
The loss of Aleppo would be the biggest blow for Syria's opposition since the conflict began in March 2011 with anti-government protests, before spiralling into a civil war.
More than 50,000 people have fled Aleppo's rebel-held districts, the Observatory said Wednesday, including at least 20,000 to government-held territory and another 30,000 to Kurdish-controlled districts.
Many others have travelled south into the remaining territory held by rebels.
Another AFP correspondent near a temporary government-run shelter on the edge of Aleppo on Wednesday saw dozens of displaced residents huddled on the back of pick-up trucks under the pounding rain.
Hundreds also massed in the newly recaptured neighbourhood of Jabal Badro to board government buses heading to west Aleppo.
"The situation of those fleeing is desperate," said Pawel Krzysiek, head of communications for the International Committee of the Red Cross (ICRC) in Syria.
Syria's Red Crescent is offering assistance in government-held areas, but does not yet have access to east Aleppo.
The UN has for months sought access to the east, but a plan it presented earlier this month to deliver aid has yet to be approved by the government.
British Foreign Minister Boris Johnson said he hoped the meeting could lead to "an end to the carnage, particularly in Aleppo".
"I would urge all those with responsibility for that, both the Assad regime and their supporters in Russia... to think of what they can do to bring peace, stop the bombardment, stop the killing of innocent civilians and get to the negotiating table," he told AFP after meeting his Cypriot counterpart in Nicosia.
Syria's opposition National Coalition said it was working with France on a draft UN resolution seeking an immediate ceasefire in Aleppo, though regime ally Russia was likely to veto such a proposal.
On Wednesday morning, 26 civilians including seven children were killed in government artillery fire on the Jubb al-Qubbeh district in east Aleppo, the Observatory said.
The White Helmets rescue group published photos of the aftermath of the shelling on Jubb al-Qubbeh, showing an apocalyptic scene with bodies, pieces of flesh, and suitcases strewn across the street.
In one image, a young man wept next to two bodies, their top halves obscured by blankets. The feet of one body were clad in pink socks, the other wore red boots done up with white laces.
The Observatory says nearly 300 civilians, including 33 children, have been killed in east Aleppo since the latest government assault began on November 15.
Another 48 civilians have been killed in west Aleppo, according to the monitor.
State news agency SANA said eight civilians including two children had been killed in rebel fire on several districts in the city's west on Wednesday.
The violence in the city has prompted international concern, though there has been little sign of a plan to intervene.
UN rights chief Zeid Ra'ad Al-Hussein on Wednesday said civilians in eastern Aleppo faced "a nightmare which clearly violates the most basic norms of human rights and any shred of human decency."
"Pounded by accelerating bombardment, deliberately deprived of food and medical care, many of them - including small children - report that they are simply waiting for death," he said.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)