Saudi Arabia says new report “vastly exaggerated” and that rebels used schools, hospitals and mosques as bases.

More than a third of Saudi-led air strikes on Yemen hit civilian sites including schools, hospitals and mosques, according to a new study.

The findings came from the Yemen Data Project, a group of security and human rights researchers, who looked into more than 8,600 air raids in the campaign between March 2015 and the end of August this year.

The results of the study were published by British newspaper The Guardian on Friday.

Out of the air raids examined, the study found that 3,577 were listed as hitting military sites and 3,158 non-military, while 1,882 strikes were classified as unknown, according to The Guardian.

Over the course of the campaign led by Saudi Arabia, the survey listed 942 air raids on residential areas, 114 on markets, 34 on mosques, 147 on school buildings, 26 on universities and 378 on transport.

The study, which the report said was based on open-source data including research on the ground, said that one particular school building was hit nine times, and one market was hit 24 times.

The project said the coalition hit more non-military sites than military in five of the past 18 months.

Riyadh dismisses report

Saudi Foreign Minister Adel al-Jubeir was quoted by The Guardian dismissing the report as “vastly exaggerated” and challenging its methodology.

He said rebel fighters had “turned schools and hospitals and mosques into command and control centres.”

“They have turned them into weapons depots in a way that they are no longer civilian targets … They are military targets. They might have been a school a year ago. But they were not a school when they were bombed,” he said.

READ MORE: What is the solution to the war in Yemen?

Saudi Arabia, along with a coalition of other Arab states, intervened in Yemen in March 2015 in support of the government of President Abd-Rabbu Mansour Hadi after Houthi rebels took over the capital Sanaa.

Since then the conflict has killed more than 6,600 people, most of them civilians, and displaced at least three million others, according to the UN.

A United Nations report in June found the coalition responsible for 60 percent of the 785 deaths of children in Yemen last year.

Fighting has intensified since the collapse of UN-backed peace talks in Kuwait on August 6.