GENEVA (Reuters) - Hundreds of Syrian men from eastern Aleppo have gone missing after leaving rebel-held areas amid reports of reprisals by soldiers including executions of people suspected of supporting the opposition, the United Nations said on Friday.
The U.N. human rights office voiced deep concern that government forces could be mistreating the missing men and said that some 150 activists feared detention if they left remaining rebel-controlled pockets of Syria's largest city.
U.N. human rights spokesman Rupert Colville also said there were reports that two rebel militias - Jabhat Fatah al-Sham, formerly known as the Nusra Front, and the Abu Amara Battalion - had during the last two weeks abducted and killed an unknown number of civilians in the city who had asked armed groups to leave their neighbourhoods to save the lives of civilians.
The Syrian army pressed an offensive in Aleppo on Friday with ground fighting and air strikes in an operation to retake all of the city's besieged rebel-held east and bring victory in the civil war closer for President Bashar al-Assad.
"There have been allegations of reprisals against civilians who are perceived to have supported armed opposition groups, as well as reports that men were being separated from women and children," Colville told a news briefing.
"We have received very worrying allegations that hundreds of men have gone missing after crossing into government-controlled areas."
The men, who are mainly between 30 and 50 years old, had not been heard from since fleeing a week to 10 days ago, he said, adding that it was not clear whether they were civilians.
"Given the terrible record of arbitrary detention, torture and enforced disappearances, we are of course deeply concerned about the fate of these individuals," Colville said.
"It could mean that some have been killed, it could mean they have been arbitrarily detained and taken somewhere, we just don't know."
Peter Maurer, president of the International Committee of the Red Cross, told reporters on Monday that the ICRC had not been able to gain access to people fleeing eastern Aleppo who were being screened or detained.
Colville cited a report that on Dec. 4 in the al-Hellok neighbourhood, "two members of the national defence forces killed four of their own male relatives in front of their families reportedly because they were perceived as having been sympathetic to the opposition".
He also said that if rebels were proven to have prevented civilians fleeing to safety, this could amount to a war crime.
"Civilians are caught between warring parties that appear to be operating in flagrant violation of international humanitarian law," said Colville.
He said tens of thousands had fled the shrinking opposition-held areas of the city, but that at least 100,000 civilians were believed to remain "in this last bastion of opposition in Aleppo".
Reporting by Stephanie Nebehay; Editing by Mark Heinrich