Attacks by Syrian regime forces and their Russian allies killed 12 civilians in the country’s northwest on Friday in the latest violation of an eight-month-old truce, a war monitor said.

The Britain-based Syrian Observatory for Human Rights said four women were among the 12 people killed in shelling and airstrikes on several towns and villages in Idlib and neighbouring Hama province.

“The attacks have been continuously escalating for four days,” Observatory head Rami Abdul Rahman told AFP.

An AFP correspondent saw intense bombardment of southern Idlib on Friday, when warplanes dropped bombs that sent huge plumes of grey smoke billowing into the sky.

Idlib and nearby areas have been protected from a massive regime offensive since a September deal inked by Damascus ally Russia and rebel backer Turkey.

But the region, currently harbouring some three million people, has come under increasing bombardment since the extremist group Hayat Tahrir al-Sham took full control of it in January.

The escalation has killed 200 civilians and displaced nearly 140,000 since February, according to the UN.

Abdul Rahman said shelling and airstrikes in recent days have primarily targeted positions and bases belonging to former Al-Qaeda affiliate HTS and other armed groups.

The UN says schools and medical centres have also been hit by the new wave of attacks.

State news agency SANA on Friday said the Syrian army “intensified” operations against HTS in Idlib and Hama, targeting armoured vehicles and rocket launchers.

The AFP correspondent saw vehicles loaded with mattresses, carpets and household appliances leaving villages in southern Idlib en route to areas closer to the Turkish border.

Residents said increased attacks have emptied some villages in southern Idlib of their residents.

“We’ve all left,” said Abu Ali, a 40-year-old man who fled the Idlib village of Kafr Ain four days ago because of bombing.

“No one is left in the village because of the shelling,” he told AFP.

The civil war in Syria has killed more than 370,000 people and displaced millions since it began in 2011 with anti-regime protests that sparked a devastating crackdown.

Schools, health facilities and residential areas have been hit by the worst barrel bombing campaign in rebel-held northwestern Syria in 15 months, the United Nations regional humanitarian coordinator Panos Moumtzis told Reuters on Thursday. Russian and Syrian forces intensified air strikes and shelling in the northwestern region overnight in the heaviest assault since it was declared a demilitarised zone under a Russian-Turkish deal, sources said earlier.

“We have information that educational facilities, health facilities and residential areas are being bombed by helicopters and planes,” Moumtzis told Reuters in Geneva. “The barrel bombing is the worst we have seen for at least 15 months.” Russian and Syrian forces intensified air strikes and shelling in rebel-held northwestern Syria overnight, the heaviest assault since the area was declared a demilitarised zone under a Russian-Turkish deal, residents and medics said on Thursday.

The targeted villages and towns in northern Hama and southern Idlib fall within a buffer zone agreed last September between Russia and Turkey as part of a deal which averted a major offensive on the area.

Schools, health facilities and residential areas have been hit, United Nations regional humanitarian coordinator Panos Moumtzis told Reuters on Thursday. “The barrel bombing is the worst we have seen for at least 15 months.” He added that 300,000 people live in the buffer zone where there are hostilities.

Earlier this week, the United States warned violence in the buffer zone “will result in the destabilisation of the region”.

Since Tuesday, attacks have forced thousands of civilians to flee to camps further north along the Turkish border and damaged four medical facilities, according to Idlib civil defence officials and a US medical aid agency working in the area.

“Medical facilities are being evacuated, leaving the most vulnerable with no access to medical care. We are on the edge of a humanitarian catastrophe,” Khaula Sawah, vice president of the US-based Union of Medical Care and Relief Organizations said in a statement on Wednesday.

Agencies