Syrian government forces and rebels clashed in the northwestern province of Hama on Friday shortly after a Russian-led deal to establish de-escalation zones took effect, a monitor and a rebel official said.

Fighter jets fired at the rebel-held village of al-Zalakiyat and nearby positions in the Hama countryside, where the combatants exchanged shelling, the Syrian Observatory for Human Rights said.

The Britain-based war monitoring group said government forces shelled the nearby towns of Kafr Zita and Latamneh. There was no immediate comment from the Syrian army.

Mohammed Rasheed, a spokesman for the Jaish al-Nasr rebel group based in Hama, confirmed that fighting had broken out after midnight.