Heavy clashes have been reported in the besieged Syrian city of Aleppo after a three-day ceasefire ended on Saturday.
The unilateral ceasefire was announced last week by Russia, which has been carrying out air strikes in support of the Syrian government.
The UK-based Syrian Observatory for Human Rights said fighting and air strikes took place on Saturday night.
There are also concerns humanitarian aid did not reach the city during the ceasefire.
The Observatory said air strikes hit a key front line in the south-west of the city on Saturday, with clashes between rebel fighters and government troops intensifying in rebel-held eastern districts of Aleppo.