Moscow has not reached an agreement with the US on safe exit for Aleppo fighters, the Russian deputy foreign minister said after rebel officials claimed a proposal had been presented by the two countries.
"The issue of withdrawing militants is the subject of separate agreements. This agreement has not yet been reached, largely because the United States insists on unacceptable terms," Sergei Ryabkov was quoted as saying by the RIA news agency on Sunday.
Ryabkov said talks between Russian and US experts would continue in Geneva, RIA reported.
"What Western agencies are reporting does not necessarily correspond with reality," Ryabkov said. He however, added that Russia was working to create the necessary conditions for the safe passage of people from Aleppo.
Rebel officials told Reuters earlier on Sunday that a proposal had been put forth for fighters to leave the embattled city with their families and other civilians.
Russia and the US have been meeting in Geneva to seek a solution to the fighting and the humanitarian crisis it has caused.
Syrian regime forces, aided by Russian aerial onslaught, have taken more than 80 percent of rebel-held eastern Aleppo, and thousands of civilians are trapped in the warzone without enough water and other basic amenities.
"The fall of Aleppo or any other city or town doesn't mean the end of the revolution. The revolution doesn't end in a city or a town ... It is an ideology and ideology will never die," Ahmed Mohammad, a Syrian activist, told Al Jazeera.
Also on Sunday, Syria's state news agency said at least 4,000 people fled the opposition-held enclave of Aleppo, some getting on government buses.
Elsewhere in Syria, the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) recaptured the ancient city of Palmyra after thousands of its fighters launched a multi-pronged assault, according to reports.
Syria's state TV said more than 70,000 of eastern Aleppo's estimated 275,000 residents have fled in recent days, mostly to government-held western Aleppo districts.
Fighters still control about 7sq km in the city's east, down from the original 45sq km they once held, according to state TV.
Residents said government air strikes hit the last remaining bridge that linked eastern and western Aleppo, a largely symbolic attack.
They also reported that government and allied troops kept up their bombing of a handful of neighbourhoods, which have become the shelter for most of the civilians who chose to remain.
The Russia-backed ground offensive, which began on November 26, followed an intensive aerial bombing campaign that knocked out most of the medical facilities, targeted civil defence and municipal vehicles and blocked roads with rubble.
The eastern Aleppo area has also been cut off from outside assistance since July by a government siege.
Fighters captured the eastern half of Aleppo, Syria's largest city and former commercial capital, in 2012.
The government's recapture of the city would mark its greatest victory since the war began in 2011.