At least 24 people have been killed in a series of Syrian government air strikes around the city of Idlib, which rebels seized earlier this month, a monitoring group said Wednesday.

Two children were among 12 people killed when a barrel bomb hit a shelter in the rebel-held town of Saraqeb, southeast of Idlib, on Tuesday, the Syrian Observatory for Human Rights said.

The regime's use of the crude unguided munitions has drawn heavy criticism because of the indiscriminate toll they cause among civilians.

A missile strike on a village southwest of Idlib killed a woman, the Britain-based Observatory said.

Inside the city, a wave of missile strikes killed 11 men, it added, without specifying whether they were rebel fighters or civilians.

The state SANA news agency cited a military source as saying that the air force had targeted "terrorist positions" in Idlib and its outskirts.

Islamist rebels, including Al-Qaeda loyalists, seized the northwestern city earlier this month after heavy fighting.

Human Rights Watch said on Tuesday that eyewitness accounts and other evidence "strongly" suggested that regime forces had dropped barrel bombs filled with toxic chemicals in the province on three occasions during the battle for Idlib.

In the southern province of Daraa, meanwhile, the Observatory said barrel bombs had killed at least 10 people on Tuesday, eight of them children.