Aid agencies called Friday on Syria's government to end its encirclement of rebel-held east Aleppo as a handful of civilians managed to use humanitarian corridors to flee the ruined city.

UN Syria envoy Staffan de Mistura, meanwhile, urged Russia to let the United Nations take charge of the corridors.
"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."
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 17, leaving an estimated 250,000 trapped without reliable access to food or medical aid.
Russia, a key ally of President Bashar al-Assad, on Thursday announced the opening of humanitarian passages for civilians and surrendering fighters seeking to exit the city's rebel-held eastern neighbourhoods.
The Red Cross welcomed the corridors but said Russia and pro-government forces had an obligation to protect everyone in Aleppo, once Syria's economic hub and a battleground city seen as key in its five-year-old conflict.
"Those who decide, for whatever reason, to stay in eastern Aleppo must be protected, and all sides must allow humanitarian agencies to reach and assess their well-being and needs," the International Committee of the Red Cross said.
Residents have reported food shortages and spiralling prices in rebel districts since regime forces cut off the opposition's main supply route into the northern city.
The US-based 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.
Russian Defence Minister Sergei Shoigu has said three humanitarian corridors were being opened "to aid civilians held hostage by terrorists and for fighters wishing to lay down their arms".

Residents holed indoors

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.
Shops were shuttered and generators in several neighbourhoods had stopped after their fuel ran out.
Ahmad Ramadan from the opposition Syrian National Coalition accused Russia and the regime of forcing civilians to flee through continued bombing raids.
"What is happening now is not battles, but the complete and systematic destruction of the city and its residents, whether they are civilians or fighters," he said.
Regime aircraft bombed eastern areas of Aleppo overnight, the Britain-based Observatory said.

 'Rebel-civilian dynamic'

Analysts say that losing Aleppo would be a major blow for the armed opposition and could signal a turning point in the conflict, which began in 2011 with the brutal crackdown of anti-government protests.
"In Aleppo, getting civilians to leave would both serve its propaganda and its military objectives," said Emile Hokayem, senior fellow at the International Institute for Strategic Studies.
"The regime uses massive, indiscriminate force to brutalise civilians to force them to kneel or reject the rebel groups," he said of regime tactics.
More than 280,000 have been killed in Syria's devastating war that has seen the spread of jihadist groups and dragged in world powers seeking to stem their growth.
A US-led coalition is conducting an aerial campaign against the Islamic State (IS) jihadist group, which despite battlefield losses still controls areas of north and northeastern Syria.
The Observatory said that the death toll from coalition strikes Thursday on the IS-controlled town of Ghandoura had risen to 28 civilians, including children.
The town is near Manbij, a strategic point on the road between Turkey and the IS bastion of Raqa, and came after the coalition opened a formal investigation to determine whether nearby air strikes last week claimed dozens of civilian lives.
IS, meanwhile, executed 24 civilians in a village close to Manbij, after seizing Buyir from a Kurdish-Arab alliance, the Observatory said.
IS's main jihadist rival Al-Nusra Front announced Thursday it was splitting from its parent organisation, Al-Qaeda.