UN human rights experts believe war crimes may have been committed by all parties to the conflict in Yemen.
In their first such report, they allege Yemeni government forces, the Saudi-led coalition backing them, and the rebel Houthi movement have made little effort to minimise civilian casualties.
They point to attacks on residential areas in which thousands have died.
The warring parties are also accused of arbitrary detentions, torture, enforced disappearances and recruiting children.
The experts will present their report to the UN Human Rights Council next month.
Why is there a war in Yemen?
Yemen has been devastated by a conflict that escalated in early 2015, when the Houthis seized control of much of the west of the country and forced President Abdrabbuh Mansour Hadi to flee abroad.
Alarmed by the rise of a group they saw as an Iranian proxy, the UAE, Saudi Arabia and seven other Arab states intervened in an attempt to restore the government. They have received logistical and intelligence support from the US, UK and France.
At least 6,660 civilians have been killed and 10,563 injured in the fighting, according to the United Nations. Thousands more civilians have died from preventable causes, including malnutrition, disease and poor health.
The fighting and a partial blockade by the coalition has also left 22 million people in need of humanitarian aid, created the world’s largest food security emergency, and led to a cholera outbreak that is thought to have affected 1.1 million people.
What are the allegations in the report?
The so-called Group of Experts note that coalition air strikes have caused most direct civilian casualties, and that they have hit residential areas, markets, funerals, weddings, detention facilities, civilian boats and medical facilities.
The report says they “have reasonable grounds to believe that individuals in the government of Yemen and the coalition may have conducted attacks in violation of the principles of distinction, proportionality and precaution that may amount to war crimes”.
They add that the naval and air restrictions imposed by the coalition on rebel-held areas to halt alleged weapons smuggling may also constitute a violation of the proportionality rule of international humanitarian law, while the effective closure of Sanaa airport may violate the principle of protection for the sick and wounded.
The experts also expressed concern at the situation in the southern city of Taiz, where the Houthis have been besieging a government-held area for three years.
Ending Yemen’s never-ending war
The girl with the strawberry ring
Who is fighting whom in Yemen?
The report says civilians, including women and children, have been hit by shelling and snipers from the Houthis and other parties while in their homes, fetching water at local wells, or on their way to purchase food or seek medical attention.
The Houthis are accused of indiscriminately using “weapons with wide area effect” in Taiz and other urban settings, which would constitute a war crime.