The UN Human Rights Council on Monday unanimously agreed to send an emergency mission to Iraq to investigate Islamic State atrocities, as Baghdad warned the country was "facing a terrorist monster".
The 47 members of the United Nations' top rights body accepted without a vote a resolution urging the probe presented by Iraq and supported by more than 100 states.
The diplomats reached their decision after spending the day listening to details of horrendous abuses and crimes attributed to the jihadist group calling itself the Islamic State, including massacres, forced conversions, abductions, slavery, sexual violence and the use of children as soldiers and suicide bombers.
"We are facing a terrorist monster," Iraqi Human Rights Minister Mohammed Shia al-Sudani told the council, decrying acts "equivalent to genocide and crimes against humanity".
The special session was called at Baghdad's request, with support from the five permanent members of the UN Security Council -- Britain, China, France, Russia and the US -- among other countries.
"The reports we have received reveal acts of inhumanity on an unimaginable scale," deputy UN rights chief Flavia Pansieri told diplomats from the 47 member states as she opened the emergency session.
The IS has grabbed large swaths of Iraq's Sunni heartland since June 9. It has also occupied parts of Syria and declared a "caliphate" in a region straddling the two countries.
The group has shocked the world with filmed massacres and beheadings, including that of US journalist James Foley.
"The stories that have emerged from ISIL's bloody assault on Iraq are the ones of nightmares," US ambassador told the UN rights body Monday, insisting it was "critically important that the council responds".
At least 1,420 people were killed in the country last month alone, according to fresh UN numbers issued Monday, while more than 1.8 million people have fled their homes since the beginning of the year.
- 'Imminent danger' -
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The UN has accused the group of committing war crimes and crimes against humanity, including "ethnic and religious cleansing", and has warned of the risk of "genocide" in parts of Iraq.
Sudani stressed that "the acts of the IS are a threat not only to Iraq but to the whole region," warning they posed "an imminent danger for all countries of the world".
Iran's ambassador Mohsen Naziri Asl also urged "all member states to unite against this threat".
The resolution adopted Monday condemned "in the strongest possible terms systematic violations and abuses of human rights and violations of international humanitarian law resulting from the terrorist acts committed by ISIL (IS) and associated groups".
It called on the office of the UN's brand new High Commissioner for Human Rights, Jordan's Prince Zeid al-Hussein, who will officially be sworn in on Thursday, to dispatch investigators to Iraq.
The fact-finding mission will count 11 investigators who should make it to Iraq within the next couple of weeks, a spokesman for the UN human rights office said.
The investigators, who will have a budget of $1.2 million, will be expected to give an update to the Council at its next regular session which starts next week, and a full report at a session starting in February.
Their aim will be to gather evidence against the IS perpetrators for use in possible future prosecution, for instance by the International Criminal Court.
Russia and China supported Monday's resolution, raising hopes that the United Nations Security Council, which refers cases to the ICC, will not remain as hopelessly deadlocked on Iraq as it has been on addressing the civil war in neighbouring Syria.
Russian representative Alexey Borodavkin meanwhile did not pull any punches, blaming the rise of IS on countries helping the opposition fight Syrian President Bashar al-Assad's regime.
"The current tragedy in Iraq is clear proof of the fact that the unlawful, external interference leading to the destruction of statehood do not give rise to democracy," he said.