The truce, which brought a halt to four months of devastating bombardment by the government and its ally Russia on Idlib province, had held despite persistent skirmishes on the ground.

But on Tuesday, Russia carried out its first air strikes in the area since the ceasefire began, according to the Syrian Observatory for Human Rights.

Bombardment continued before dawn on Wednesday in the village of Al-Daher where a 75-year-old man was killed, the Britain-based monitor said, adding that the air raids had since stopped.

The victim -- Ahmad Issa al-Moussa -- had been displaced to Idlib from Syria's second city of Aleppo several years ago, an AFP correspondent said.

"We were asleep... when we heard the sound of a missile falling 50 metres away," said Abu Anas, the victim's son.

The 31-year-old man said his father was slow to evacuate their home because of difficulty walking.

He died when a second air strike hit two metres away from him, the son added.

The truce was the second such agreement between the Syrian government and jihadists since August 1. The previous one collapsed after just a few days.

The Hayat Tahrir al-Sham alliance led by Al-Qaeda's former Syria affiliate controls most of Idlib as well as parts of neighbouring Aleppo and Latakia provinces.

The region of around three million people is one of the last holdouts of opposition to forces of Syrian President Bashar al-Assad.