There are new reports from Syria of atrocities in Aleppo.

As many people try to flee the city, the UN cites “multiple sources” as saying dozens of civilians have been killed as the Syrian army and its allies seal their control of the city.

The United Nations human rights spokesman Rupert Colville said it looked like “a complete meltdown of humanity”.

Pro-government forces are said to have entered homes and killed people on the spot – including women and children.

The reports speak of 82 civilians having died in four different neighbourhoods.

Turkey has said it will intensify its contacts with Russia and other countries to install a ceasefire in Aleppo and find a solution to what it calls a “humanitarian tragedy”.

The UN says it’s filled with the deepest foreboding for those who remain in the “hellish corner” of the city’s besieged areas.

Earlier, Syrian government troops said they had retaken almost all of rebel-held territory in eastern Aleppo.

On Monday the UN said hundreds of men had gone missing. Rupert Colville added that there were reports two rebel militias – the Nusra Front, and the Abu Amara Battalion – had abducted and killed an unknown number of civilians who had asked them to leave.

Messages from Aleppo residents: 'Where is humanity?', 'Where is the world?', 'Why is nobody helping us?' https://t.co/a8ayOdqA8Q pic.twitter.com/XmOZOeHu92— Al Jazeera English (@AJEnglish) December 13, 2016