As Syrian government artillery pummelled the rebel territory in Aleppo, the UN rights office said both sides appeared to be operating in "flagrant violation of international humanitarian law", and that civilians were paying the price.
"While it's very difficult to establish the facts in such a fluid and dangerous situation, we have received very worrying allegations that hundreds of men have gone missing after crossing into government-controlled areas," spokesman Rupert Colville told reporters in Geneva.
"Given the terrible record of arbitrary detention, torture and enforced disappearances by the Syrian government, we are of course deeply concerned about the fate of these individuals," Colville said.
His comments came as Syrian government artillery bombarded the fast-shrinking rebel enclave in the heart of Aleppo today.
Also Read
The army has recaptured 85 percent of the eastern sector of the city which the rebels had held since summer 2012.
The assault has also prompted a mass exodus from east Aleppo where at least 80,000 people have fled their homes, according to the monitor.
Colville warned that "there have been allegations of reprisals against civilians who are perceived to have supported armed opposition groups" as they fled into government-held areas.
He said some 150 activists remained stranded inside opposition-controlled Aleppo due to fears of being detained by government forces if they attempt to leave.
Colville said today that more than 100,000 people were believed to remain inside the areas controlled by the opposition in east Aleppo, but warned the situation was very fluid and the numbers were unclear.
Disclaimer: No Business Standard Journalist was involved in creation of this content