Fighting raged near a military base in Syria's north as a cease-fire in the bloody civil war began on Friday at dawn, activists said, illustrating the difficulty of enforcing even a limited truce coinciding with a Muslim holiday.

Elsewhere, violence appeared to die down, and thousands of protesters took advantage of the lull to mount some of the largest anti-government demonstrations in months.

The truce, proposed by UN-Arab League envoy Lakhdar Brahimi and endorsed by the Security Council, is set for only the four days of the Eid al-Adha holiday, has no monitoring mechanism and no stated plans for its aftermath.