The UN has suspended peace talks aimed at ending Syria's five-year civil war, just days after they began.
But the organisation's special envoy Staffan de Mistura insisted negotiations had not failed and would resume on 25 February.
Each side blamed the other for the collapse of the round.
It came as the Syrian government said it had dealt a major blow to the opposition by cutting a key supply route to the rebel-held city of Aleppo.
Syrian state television reported that government forces had broken the siege of Nubul and Zahraa, two town’s north-west of Aleppo.