File photo of a Free Syrian Army soldier standing on a damaged Syrian military tank in front of a damaged mosque, which were destroyed during fighting with government forces.

A ceasefire in northwest Syria, part of a wider deal that included cessation of hostilities in the area as well as in a town near the Lebanese border, was broken late on Saturday, a monitoring group said.

Shells apparently fired by insurgents hit the village of al-Foua in the northwestern province of Idlib, the Syrian Observatory for Human Rights said, after rebels blamed government forces for violating the ceasefire by dropping barrel bombs on an area nearby.

Warring sides had agreed on a ceasefire in al-Foua and next-door Kefraya, two villages held by pro-government forces and besieged by rebels, as well as in the town of Zabadani near the Lebanese border, where insurgents are holed up and surrounded by government forces.

But shelling of al-Foua resumed, the Observatory said, with no immediate casualties reported.

The shelling came after an online statement purportedly from insurgents in the area that blamed the government for violating the ceasefire by dropping barrel bombs on the nearby village Taftanaz.

The statement said insurgents retaliated by firing at al-Foua and Kefraya.

The Observatory said explosions had been heard in Taftanaz, with activists blaming government barrel bombs for killing at least five people there. It was unclear if Taftanaz had been included in the ceasefire agreement.

The leader of Lebanese Shiite group Hezbollah, which backs Syrian government forces, confirmed on Friday that a long-term ceasefire deal had been reached which would include withdrawal of rebel fighters from Zabadani in exchange for the evacuation of civilians from al-Foua and Kefraya.