LONDON (Thomson Reuters Foundation) - Aid agency Medecins Sans Frontieres (MSF) called on Monday for a full investigation into an attack on a hospital in Yemen this month in which it says six people were killed and at least seven wounded, mostly medical staff and patients.

The charity - which has seen two hospitals, a clinic and an ambulance hit in Yemen in the last three months - said the conflict was being fought “with total disregard for the rules of war”.

“The way war is being waged in Yemen is causing enormous suffering and shows that the warring parties do not recognize or respect the protected status of hospitals and medical facilities,” said MSF Director of Operations Raquel Ayora.

“We witness the devastating consequences of this on people trapped in conflict zones on a daily basis.”

A mostly Arab coalition led by Saudi Arabia is fighting Iran-allied Houthi militia who control Yemen’s capital.

Nearly 6,000 people have been killed, around half of them civilians, since the coalition began air strikes last March.

“Public places are being bombed and shelled on a massive scale,” Ayora said. “Not even hospitals are being spared, even though medical facilities are explicitly protected by international humanitarian law.”

The charity has asked the International Humanitarian Fact-Finding Commission (IHFFC) to conduct an investigation into an attack on Shiara hospital in Saada Province, northwestern Yemen, on Jan 10.

MSF, also known as Doctors Without Borders, has said the hospital was hit by a projectile but could not confirm its origin.

The call for an inquiry comes after another attack on Friday in which an ambulance driver was among at least six people killed in strikes near Saada city. The ambulance was hit as it arrived at the site of an earlier bombing.

MSF said coalition jets had bombed Haydan hospital in Saada Province in October and a mobile clinic was hit in a strike in Taiz in southern Yemen in December, wounding eight, including two MSF staff.

The charity said all warring parties had been given the GPS coordinates of medical sites where MSF works. It said it had not received an explanation for any of the incidents.

The Berne-based IHFFC investigates allegations of serious violations of international humanitarian law under the Geneva Conventions.

MSF has also called for an independent inquiry into the U.S. bombing of Kunduz hospital in Afghanistan on Oct. 3 which killed 30 people. The charity is waiting to hear whether the U.S. government will consent to the investigation.

“We urgently need guarantees from warring parties that functioning hospitals are never a legitimate target,” MSF President Joanne Liu said.

“Is this the new normal: an MSF hospital bombed every month? How many other hospitals are being attacked in Yemen and other conflict zones, run by medical staff who do not have the platform that MSF does to speak out?”

MSF is managing 11 hospitals and health centers in Yemen and supporting another 18 health centers. It has treated more than 20,000 wounded since March.