"We affirm the inaccuracies in the report and its non-neutrality," the coalition said in a statement released by the official Saudi Press Agency.

"The report did not mention Iran's role in the continuation of the war... and its continued support for the Huthi" militias.

The coalition added that it would later provide a "comprehensive and detailed legal response" to the report.

In their first report released on Tuesday, a team of UN-mandated investigators said all parties in Yemen's bloody conflict have committed a "substantial number of violations of international humanitarian law".

Many of these violations may amount to "war crimes", the report said, pointing to widespread arbitrary detention, rape and torture.

The report said coalition air strikes had caused "most of the documented civilian casualties", pointing to a large number of strikes on residential areas, markets, funerals, weddings and medical facilities.

It said there were "serious concerns about the targeting process applied by the coalition," pointing out that in many cases there were no apparent military targets in the vicinity of the attacks.

Yemen's devastating conflict has left nearly 10,000 people dead since March 2015, when a Saudi-led coalition intervened to fight Huthi rebels closing in on the last bastion of President Abedrabbo Mansour Hadi's government.

The UN human rights office said Tuesday that some 6,660 civilians were among the dead, while more than 10,500 had been injured.

The UN has already described the situation in Yemen as world's worst humanitarian crisis.

UN-backed talks between Yemen's government and the Iran-aligned Huthi militias are to open in Geneva on September 6 -- a first step toward resuming peace negotiations that broke down two years ago.