A ceasefire in Syria brokered by Russia and the US appeared to be holding on its first full day Tuesday (September 13th), AFP reported.

Guns fell silent at sundown Monday as part of an agreement to bring an end to fighting between regime forces and a range of opposition groups, excluding extremist groups like the "Islamic State of Iraq and the Levant" (ISIL).

In Aleppo city, the night and early morning passed without airstrikes or rocket fire.

Damascus and its opposition-controlled suburbs also reported quiet, with residents taking advantage of the lull in violence to mark Eid al-Adha.

The Syrian Observatory for Human Rights said the main battlefronts were "completely calm".

Syrian state media reported several alleged opposition violations of the ceasefire in Homs province and south of Aleppo city, but there were no reports of significant violence or casualties.

The deal calls for the truce to be renewed every 48 hours, and immediate humanitarian aid access, particularly to civilians living under siege.

The UN said Tuesday it had readied help for civilians but aid convoys would not roll until security was assured.

If the truce holds for a week, Russia and the US will begin a joint campaign to target extremists, including ISIL and former al-Qaeda affiliate Fateh al-Sham Front.