Three experts working for the UN's top human rights body say the governments of Yemen, the United Arab Emirates and Saudi Arabia may have been responsible for war crimes including rape, torture, disappearances and "deprivation of the right to life" during three and a half years of escalated fighting against rebels in Yemen.

In their first report for the Human Rights Council, the experts also point to possible crimes by rebel Shia militia in Yemen, which has been fighting the Saudi-led coalition and Yemen's government since March 2015.

The experts have also chronicled the damages from coalition air strikes, the single most lethal force in the fighting, over the last year.

They urged the international community to "refrain from providing arms that could be used in the conflict" — an apparent reference to countries like the United States and Britain that help arm the Saudi-led coalition, as well as Iran, which the coalition has accused of arming the Houthis.

The experts visited some but not all parts of Yemen as they compiled the report.

"[We have] reasonable grounds to believe that the governments of Yemen, the United Arab Emirates and Saudi Arabia are responsible for human rights violations," the report said. It cited violations including unlawful deprivation of the right to life, arbitrary detention, rape, torture, enforced disappearances and child recruitment.

Women walk past a building destroyed by a Saudi-led airstrike in Yemen's capital Sanaa in September 2015. The UN's humanitarian aid agency has called Yemen the world's worst humanitarian crisis. (Khaled Abdullah/Reuters)

Saudis, U.A.E. respond

Abdulaziz al-Alwasil, the Saudi ambassador to the UN in Geneva, said the report was "not accurate" and overlooked the bigger picture of an armed Houthi militia illegally seizing territory from an internationally recognized government and at times firing missiles in Saudi Arabia.

"It [the report] is surprising for us because it doesn't reflect the reality," he said. "We genuinely want to improve the situation in Yemen: We are spending money there, our people are getting killed there. And Yemen is not a wealthy state, it's just our neighbour. And we think it is our responsibility to make sure that this country is not used to attack the neighbouring countries."

"I don't think it's going to have a major impact in the way that we review our procedures or the way we conduct our military operations," he said.

A picture taken during a trip in Yemen organized by the U.A.E.'s National Media Council shows a Yemeni military patrol boat in Mukalla, the southeastern capital and supply port of Hadramawt province on Aug. 8. (Karim Sahib/AFP/Getty Images)

On Twitter, Emirati Minister of State for Foreign Affairs Anwar Gargash wrote that the U.A.E. "must review it, answer its merits and review what it says about the horrors of the Houthis."

Defending American support for the Saudi-led coalition, U.S. Defence Secretary James Mattis said that his country's efforts to minimize civilian casualties are paying off, despite the report's findings.

"We have not seen any callous disregard by the people we're working with," Mattis said. "So we will continue to work with them."

Confidential list of suspects

The Associated Press reported last year that the U.A.E. and its allied militias were running a network of secret detention facilities, beyond the control of Yemeni government. In June, AP revealed that hundreds of detainees had been subjected to sexual abuse and torture.

The UN report accused the "de facto authorities" — an allusion to rebel leaders that control some of the country's most populated western and northern areas — of crimes including arbitrary detentions, torture and child recruitment. Human rights advocates have faulted the Houthis for laying land mines and targeting religious minorities and imprisoned opponents.

Soldiers from the Saudi-led coalition secure a street in Yemen's southern port city of Aden in September 2016. The UN-backed experts are urging the international community to 'refrain from providing arms that could be used in the conflict.' (Faisal Al Nasser/Reuters)

Kamel Jendoubi, a Tunisian human rights advocate who chaired the group of experts, said they compiled a "confidential list" of people suspected of committing international crimes, which was being handed over to the office of the UN human rights chief on Tuesday. His team refused to indicate how many or which people or groups were on the list — whether on the government or rebel sides.

"Despite the gravity of the situation, we still note a total disdain for the suffering of the Yemeni people," Jendoubi told reporters in a briefing on the report Tuesday. "This conflict has in effect fallen into the void."

Since March last year, the UN's humanitarian aid agency has called Yemen the world's worst humanitarian crisis — with three-fourths of its population of over 20 million in need of humanitarian assistance. The war has devastated the country's health system and provided the breeding grounds for the world's largest cholera outbreak last year.

The experts cited some 6,475 deaths from the conflict between March 2015 and June this year, but said the "real figure is likely to be significantly higher."

They also sharply criticized work by the coalition's Joint Incidents Assessment Team, which was set up as a bulwark against possible rights violations. They questioned the JIAT's explanations for the air strikes that have killed civilians, and challenged its "independence and its ability to carry out impartial investigations."

Yemenis work to bury children killed when their bus was hit during a Saudi-led coalition air strike earlier this month. (AFP/Getty Images)

The experts also said nearly a dozen deadly airstrikes they investigated over the last year "raise serious questions about the targeting process applied by the coalition." They chastised some in-the-field coalition combatants for "routinely" failing to seek information about official "no-strike" lists that should have been avoided.

Even getting the expert probe up and running was an accomplishment for the UN-backed Human Rights Council, which passed a resolution creating the team last September. Largely due to the objections of Saudi Arabia and its allies, the council failed several times to authorize more intrusive investigation into possible war crimes in Yemen. The 47-member body only last fall reached a compromise to bring in the experts.

With files from Reuters