UN Secretary General Antonio Guterres on Thursday (July 11th) strongly condemned airstrikes in north-west Syria following reports that four health facilities were hit during a single day of bombing, AFP reported.

An ambulance centre, a clinic and two hospitals, including one in Maarat al-Numan that is among the largest in the area, were attacked Wednesday, said the Union of Medical Care and Relief Organisations, a Syrian doctors' group.

"Civilians and civilian infrastructure, including medical facilities, must be protected," said Guterres in a statement released by his spokesman.

The UN had shared the co-ordinates of the hospital in Maarat al-Numan with the warring parties, the statement said.

"Parties to the conflict must respect their obligations under international humanitarian law," Guterres said, adding that those behind the attacks must be held accountable.

Backed by Russia, Syrian forces have since late April ramped up bombardment of the Idlib region, which is controlled by extremist alliance Tahrir al-Sham.

The UN has warned that an all-out offensive to push out the alliance could lead to a bloodbath in the region, where some three million people live.

More than 23 hospitals have been hit by strikes since late April.