An AFP photographer at the scene reported seeing several bodies being taken away from a wrecked home in Maarat al-Naasan, an area close to government-controlled territory.

"The shell fell on a civilian home," said the Syrian Observatory for Human Rights, a Britain-based group with a network of sources on the ground in the war-torn country.

The monitor said two women and two children were among those killed, who were all from the same family. Many others were wounded.

The shelling had begun at around 1130 GMT, with more shells fired intermittently afterwards, the AFP photographer said.

The Idlib region bordering Turkey is home to about three million people and it is one of the last pockets to oppose Damascus.

Hayat Tahrir al-Sham, a former Syrian branch of Al-Qaeda, controls with its allies about half of the region and parts of neighbouring provinces.

After a months-long military campaign to flush out the enclave sparked fears of the war's worst bloodshed yet, a ceasefire deal was reached in March 2020.

The agreement brokered by the regime and the rebels' main backers -- Russia and Turkey respectively -- has largely held since, despite sporadic flare-ups.

But Damascus has intensified attacks on southern Idlib since June.

The war in Syria has killed around half a million people and displaced millions more, the Observatory says.