A four-day ceasefire to mark the Muslim holiday of Eid al-Adha has come into effect in Syria, but the army warns it will retaliate against rebel attacks.
It was proposed by UN and Arab League envoy Lakhdar Brahimi, who hopes it will lead to a peace process.
The truce began at 06:00 (04:00 GMT), reported Syrian TV. Previous attempts at ceasefires in Syria have collapsed.
On Thursday rebels advanced into central areas of Aleppo, Syria's largest city and a key battleground.