UN chief warns of Aleppo 'atrocities'

US Secretary-General Ban Ki-moon has voiced alarm "over reports of atrocities against a large number of civilians" in Syria's city of Aleppo.

Mr Ban urged all the sides, particularly Syria's government and its allies, to protect civilians.

UN humanitarian adviser Jan Egeland earlier said Syria and Russia were "accountable" for any atrocities committed by pro-government militias.

Major gains by Syria's army have left Aleppo rebels on the brink of defeat.