Jihadists from the Islamic State (IS) group may have committed genocide and war crimes against the minority Yazidi community in Iraq, the UN says.
In a new report, it says IS had "the intent... to destroy the Yazidi as a group."
Tens of thousands of Yazidis fled villages in northern Iraq amid IS advances last summer. Many were killed or captured and enslaved.
Yazidis follow an ancient faith that jihadists regard as devil worship.
The report, commissioned by the UN Office of the High Commissioner for Human Rights, was based on more than 100 interviews with survivors of attacks in Iraq between June 2014 and February this year.
Among the atrocities it says were perpetrated against the Yazidi community by IS (also known as ISIL), were:
- the "brutal and targeted" killing of hundreds of men and boys in Nineveh province, northwest of Baghdad, in August 2014;
- the rape of girls as young as six;
- the abduction of women "as spoils of war";
- the forced separation of families, with boys as young as eight taken to be trained as IS fighters.
The reports adds: "In some instances, villages were entirely emptied of their Yazidi population."
A statement by the OHCHR says: "One witness described how two ISIL members sat laughing as two teenage girls were raped in the next room.
"A pregnant woman, repeatedly raped by an ISIL 'doctor' over a period of two-and-a-half months, said he deliberately sat on her stomach.
"He told her: 'This baby should die because it is an infidel; I can make a Muslim baby'. "
The plight of the Yazidi population was brought to international attention when IS captured the town of Sinjar in August 2014.
Thousands of residents, mainly Yazidis, were forced to flee.
Many were trapped on nearby Mount Sinjar, which was surrounded by IS fighters.
Airstrikes led by the Unites States, and an offensive led by Kurdish peshmerga forces, helped break the stranglehold on Mount Sinjar.
Who are the Yazidis?
- Religious sect found in northern Iraq, Syria and the Caucasus
- Religion incorporates elements of many faiths, including Zoroastrianism
- Principal divine figure, Malak Taus (Peacock Angel), is the supreme angel of the seven angels who ruled the universe after it was created by God
- Many Muslims and other groups incorrectly view Yazidis as devil worshippers
- There are estimated to be around 500,000 Yazidis worldwide, most living in Iraq's Nineveh plains
- In August 2007 jihadists attacked Yazidi villages in Nineveh, killing between 400 and 700 people
As well as looking into offences against the Yazidi community, investigators reported on crimes against other ethnic groups.
The report says 600 male prisoners - mainly Shia Muslims - were driven to a ravine in June 2014 and shot. It says some survived because bodies fell on top of them. Islamic State considers Shia Muslims as heretics.
On 12 June 2014, the report adds, between 1,500 and 1,700 cadets from the Speicher army base, near Tikrit, were killed after surrendering to IS fighters.
Iraqi government reports into both massacres have not yet been made public.
The report also warns of offences being committed by Iraqi security forces and affiliated militia.
It says they "carried out extrajudicial killings, torture, abductions and forcibly displaced a large number of people, often with impunity." It adds that they "may have committed war crimes".
Iraq's government has not yet responded to the report.
Iraq is not currently a member of the International Criminal Court in The Hague. If any crimes there were to be investigated by the ICC, Iraq would have to become a member.
Any offences defined as international crimes by the ICC would also have to be criminalised under Iraq's domestic laws.
The report urges Iraq to join the ICC, and also calls on the UN Security Council to refer the case to The Hague.