Idlib's civil defence, a rescue service in opposition-controlled territory known as the White Helmets, says air strikes over the past 24 hours have hit several villages in the northwestern province.

Damaged buildings are seen after alleged Russian and Assad regime airstrikes hit Kafr district of Syria's Idlib province which is a part of a de-escalation zone. January 28, 2018.
Damaged buildings are seen after alleged Russian and Assad regime airstrikes hit Kafr district of Syria's Idlib province which is a part of a de-escalation zone. January 28, 2018. (Ubeyde Fadil / AA)

Regime airstrikes have killed 33 civilians over the past 24 hours in Syria's northwestern province of Idlib where Bashar al Assad's forces are fighting militants, a war monitor said on Monday.

On Monday alone, the strikes killed 16 civilians including 11 in the town of Saraqeb's vegetable market, the Britain-based Syrian Observatory for Human Rights said.

Seventeen others were killed on Sunday in raids on various areas of the province, large parts of which are controlled by Hayat Tahrir al Sham (HTS), which is dominated by Al Qaeda's former Syria affiliate.

"Regime warplanes have intensified their strikes over the past 24 hours after relative calm due to bad weather," Observatory chief Rami Abdul Rahman said.

Syrian regime troops had been advancing on Idlib as part of a fierce offensive launched in late December with Russian backing.

At the market in Saraqeb, an AFP correspondent saw pools of blood on the ground. Small trucks loaded with sacks of potatoes stood abandoned after their windows were blasted from their frames.

In front of a hospital in the town, a motorbike and a car were trapped below the rubble and twisted metal.

Smoke rises after an air strike over Saraqib town of Idlib in Syria on January 28, 2018.
Smoke rises after an air strike over Saraqib town of Idlib in Syria on January 28, 2018. (AA)

An alliance of opposition militants and civilians overran the vast majority of Idlib province in 2015.

On January 21, Syrian regime forces said it had captured the vital military airport of Abu Duhur on the edge of Idlib province, in a breakthrough for the regime in the last Syrian province beyond its control.

With the airport's capture, the army said, troops would secure a key route leading from the neighbouring province of Aleppo south to the capital Damascus.

Syria's war has killed more than 400,000 people and displaced millions since it began in March 2011 with the brutal repression of anti-regime protests.

Source: AA