Human Rights Watch has accused Damascus of war crimes in last month's run-up to a UN-brokered truce.
The New York-based rights watchdog said 95 civilians had been killed -- many allegedly by execution -- and hundreds of homes destroyed in the northern province of Idlib in March and April when talks were under way with international envoy Kofi Annan.
The charges come after rebels reportedly killed 15 security force members during an ambush in the northern province of Aleppo.
Two rebel militiamen reportedly died in clashes sparked by the ambush.
Russia accused "terrorists" of trying to "destabilize the situation and disrupt...Annan's plan."
And in an apparent concession to the thousands of Syrians who have avoided military service since the violence began last year, President Bashar al-Assad has announced an amnesty for draft-dodgers.
Based on reporting by Reuters