Aid agencies called Friday (July 29th) on the Syrian regime to end its encirclement of rebel-held east Aleppo as a handful of civilians managed to use humanitarian corridors to flee the ruined city, AFP reported.

UN Syria envoy Staffan de Mistura, meanwhile, urged Russia to let the United Nations take charge of the humanitarian corridors that Russia proposed Thursday for civilians and surrendering fighters seeking to exit the city's rebel-held eastern neighbourhoods.

"Our suggestion is to Russia to actually leave the corridors being established at their initiative to us," he said.

"How can you expect people to want to walk through a corridor, thousands of them, while there is shelling, bombing fighting," he said.

France, meanwhile, said corridors out of the city were not "a credible response to the situation" and residents should be able to receive aid at home.

Pro-regime forces have surrounded Aleppo's eastern districts since July 17th, leaving an estimated 250,000 trapped without reliable access to food or medical aid.

The International Rescue Committee said those left behind in east Aleppo risked starvation and called for a humanitarian pause in fighting.

"The people of Aleppo should not be forced to choose between fleeing their homes and remaining under attack in a besieged area," said IRC's acting Middle East director Zoe Daniels.

But only a few Aleppo residents were able to leave eastern neighbourhoods through the passages before rebels prevented them from fleeing, according to the Syrian Observatory for Human Rights.

"Around 12 people managed to use the Bustan al-Qasr corridor before rebel groups reinforced security measures and prevented families from approaching the corridors," the monitoring group's head Rami Abdel Rahman said.

An AFP correspondent in east Aleppo said streets were empty on Friday morning, with residents holed up indoors.