The strikes targeted the village of Jubass near the town of Saraqeb in southern Idlib province, killing civilians sheltering in and near a school, the Syrian Observatory for Human Rights said.

Since Thursday, regime forces supported by Russian airstrikes have taken control of dozens of towns and villages in the area.

They are now less than four kilometres (two miles) from the strategic city of Maaret al-Numan, the head of the Britain-based monitor, Rami Abdel Rahman, told AFP.

On Tuesday, jihadist fighters and rebels managed to retake Talmanes and an adjacent village, said the Observatory, which relies on a network of sources across Syria.

Idlib is dominated by the country's former Al-Qaeda affiliate, Hayat Tahrir al-Sham. The region hosts some three million people including many displaced by years of violence in other parts of Syria.

The Damascus regime, which now controls 70 percent of Syria, has repeatedly vowed to take back the area.

Backed by Moscow, Damascus launched a blistering offensive against Idlib in April, killing around 1,000 civilians and displacing more than 400,000 people.

Despite a ceasefire announced in August, the bombardment has continued, killing hundreds of civilians and fighters.

Syria's war has killed over 370,000 people and displaced millions since beginning in 2011 with the brutal repression of anti-government protests.