As international alarm grew over the plight of residents including women, children, the sick and wounded, the UN Security Council was to vote on whether to send observers to the battleground city.
An AFP correspondent who visited a hospital in the rebel sector saw appalling conditions with patients lying on the floor without food or water and almost no heating despite sub-zero temperatures at night.
Thousands of civilians and rebels had begun leaving Aleppo on Thursday under an evacuation deal allowing Syria's regime to take full control of the divided city after years of fighting.
But the operation was suspended the next day with both sides blaming each other.
The main obstacle to a resumption is a rift over the number of people to be evacuated in parallel from two Shiite villages, Fuaa and Kafraya, under rebel siege in northwestern Syria.
Under an agreement reached between Turkey, which backs the rebels, and regime allies Russia and Iran, those evacuations would take place at the same time as the Aleppo operation.
But differences remain over the number of people to leave the villages -- the rebels have agreed to 1,500 while Shiite Iran wants 4,000 people to be allowed out.
Al-Farook Abu Bakr, of the hardline Islamist rebel group Ahrar al-Sham, said a deal had been reached for the evacuations to resume and it was possible that they would happen on Sunday.
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UN to vote on Aleppo observers as 'thousands' await evacuation
The UN Security Council was set to meet at 1600 GMT in New York to vote on French proposals to dispatch monitors to oversee evacuations and report on the protection of civilians.
The draft text said the council was "alarmed" by the worsening humanitarian crisis in Aleppo and by the fact that "tens of thousands of besieged Aleppo inhabitants" are in need of aid and evacuation.
"Our goal through this resolution is to avoid another Srebrenica in this phase immediately following the military operations," French Ambassador Francois Delattre told AFP, referring to a 1995 Bosnian war massacre.
But the proposals face resistance from veto-wielding Russia, a key backer of Syrian President Bashar al-Assad.
Families have been sheltering during the night in freezing temperatures in bombed out apartment blocks in Aleppo's Al-Amiriyah district, the departure point for evacuations before they were halted.
The green government buses that managed to evacuate hundreds before the suspension by the Syrian government. Source: AAP
No food, water
Abu Omar said that after waiting outside in the cold for nine hours the previous day, he had returned on Saturday only to be told the buses were not coming.
"There's no more food or drinking water, and the situation is getting worse by the day," he said, adding that his four children were sick because of the cold.
Dozens of trucks with humanitarian aid crossed the Turkish border Saturday into Syria, piling supplies in a buffer zone.
Aleppo has seen some of the worst violence of the nearly six-year war that has killed more than 310,000 people.
UN envoy Staffan de Mistura estimated that as of Thursday around 40,000 civilians and perhaps as many as 5,000 opposition fighters remained in Aleppo's rebel enclave.
The International Committee of the Red Cross (ICRC) appealed for safe passage for the civilians still trapped in the city.
"People have suffered a lot. Please come to an agreement and help save thousands of lives," said ICRC Syria delegation head Marianne Gasser.
"We cannot abandon these people."
Syrian and Iranian migrants hold pictures of President Bashar Assad and supreme leader Ayatollah Ali Khamenei during a protest against the war in Aleppo Source: AAP
A Turkish official said 90 wounded from Aleppo have crossed into Turkey for treatment since Thursday.
Before evacuations were suspended around 8,500 people, including some 3,000 fighters, left for rebel-held territory elsewhere in the north, said the Syrian Observatory for Human Rights.
On Friday, a convoy of evacuees that had already left east Aleppo when the operation was suspended was forced to turn back.
The ICRC, supervising the evacuations, said it was looking into reports of shooting before the convoy was turned around.
The main regional supporters of the rival sides in the devastating civil war have engaged in a flurry of diplomacy to try to secure a resumption of evacuations.
The official Iranian news agency IRNA said the foreign ministers of Russia, Turkey and Iran would meet Tuesday in Moscow to discuss the conflict.
