Forces loyal to Syrian President Bashar Al-Assad killed 111 civilians in the northwestern province of Idlib on Tuesday.

The Syrian Observatory for Human Rights gave the revised toll in a statement sent to AFP on Wednesday, a day after reporting the deaths of 37 civilians and at least 100 army deserters in the same province, a Britain-based rights group said.

The violence marks one of the deadliest days since a military assault on the central city of Hama killed 139 people in late July.

The report comes before the scheduled arrival in Syria of an advance team of Arab observers to lay the ground for monitors overseeing implementation of an Arab League deal to stop the bloodshed.