An escalation in attacks on northwest Syria has displaced more than 150,000 people in the past week, the UN said on Tuesday, as the regime and Russia stepped up bombardment.

"We are alarmed by ongoing reports of aerial attacks on population centres and civilian infrastructure, resulting in hundreds of civilians dead and injured," said David Swanson of the UN Office for the Coordination of Humanitarian Affairs, or OCHA. "More than 152,000 women, children and men have been displaced in Aleppo and Idlib governorates over the past week alone," he told AFP.

The northwestern part of Syria controlled by jihadists is made up a large part of Idlib province, as well as adjacent parts of the Aleppo and Hama provinces.

The Idlib region has been protected from a massive regime offensive by a September deal inked by Damascus ally Russia and rebel backer Turkey.

But the region of some three million people has come under increasing bombardment since the jihadist Hayat Tahrir al-Sham group, a former Al-Qaeda affiliate, took full control of it in January.

The UN humanitarian agency on Tuesday expressed alarm at health facilities being hit in the bombardment.

"Between 29 April and 6 May, at least 12 health facilities were hit by airstrikes in northern Hama and Idlib governorates, damaging health infrastructure that provided essential health services to over 100,000 people," OCHA said in a statement.

All 12 were out of service, Swanson said, while three health workers had been killed in the bombardment.

"Ongoing reports of attacks on health facilities in the region reflect a worrying trend, depriving thousands women, children and men of life-saving medical assistance," he said.

The civil war in Syria has killed more than 370,000 people and displaced millions since it began.

(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)