“After the increase of violations by regime forces that included targeting displaced people and continuous bombing of residential neighbourhoods, we declare the start of the battle in response,” said a statement signed by 10 armed rebel groups.
The truce, brokered by Russia and the United States, has seen violence dip significantly across Syria but fighting has recently flared in several regions, particularly around second city Aleppo.
Among the groups to sign the Monday statement was Jaish al-Islam, the most powerful rebel faction in Eastern Ghouta, an opposition stronghold east of Damascus.
A key figure in Jaish al-Islam is Mohammed Alloush, who is also the chief negotiator for Syria’s main opposition body, which is currently participating in UN-brokered peace talks in Geneva.
Alloush on Sunday called for renewed attacks on regime forces, despite the shaky truce.
“Don’t trust the regime and don’t wait for their pity,” he wrote on Twitter. “Strike them at their necks (kill them). Strike them everywhere.”
Also among the signatories was Ahrar al-Sham, a powerful Islamist group that has been fighting alongside Al-Qaeda’s local affiliate around Aleppo.