Five children were among those killed when the strikes hit the area of Zardana in the northwestern Idlib province late Thursday, the Syrian Observatory for Human Rights monitoring group said.

Zardana is largely controlled by Islamist rebels, with a small presence of the Hayat Tahrir al-Sham alliance led by Syria's former Al-Qaeda affiliate.

An AFP correspondent at the scene saw volunteers and a crane continue to search the rubble for bodies in the early morning.

Half a dozen men in civilian clothes helped carry a person in a black body bag away from the site of the strikes, which pulverised several buildings.

At night, dozens of wounded streamed in to the local hospital, including women, children, the elderly and rescue volunteers, the correspondent said.

The twisted bodies of the deceased lay covered in a fine light grey dust and dashed with bright red blood amid the rubble.

Most of Idlib province lies beyond government control and is held by an array of rebels and jihadists.

Since Russia intervened on its side in 2015, the Syrian regime has regained control of around half of the country.

More than 350,000 people have been killed in Syria's war since it started in 2011 with the brutal repression of anti-government protests.

The Observatory says it relies on sources inside Syria for its information, and determines who carried out strikes according to flight patterns, as well as planes and ammunition involved.