The Islamic State militants have taken a staggering 3,500 Iraqis, including women and children, as slaves, the Unite Nations has said.
Most of the enslaved are from the Yazidi minority community who were captured by the Daesh militants in 2014. There were reports earlier that hundreds of Yazidi women were conscripted into sexual slavery by the militants who control vast territories in Syria and Iraq.
The slave population also comprises around 800 Iraqi children from the city of Mosul, who have been pushed into forced military training.
The latest report also says hundreds of children were executed by the terror outfit as they tried to flee the fighting.
It said at least 18,802 Iraqis have been killed by the Isis and as many as 36,245 wounded. However, officials have said the numbers belie the actual suffering of the Iraqis at the hands of the militants.
"Even the obscene casualty figures fail to accurately reflect exactly how terribly civilians are suffering in Iraq," said Zeid Ra'ad Al Hussein, the UN's human rights chief.
"The figures capture those who were killed or maimed by overt violence, but countless others have died from the lack of access to basic food, water or medical care."
The report has also documented the gruesome ways in which Isis treats its prisoners and opponents. The barbaric methods of execution include public beheadings, running people over with bulldozers, burning them alive and throwing them off buildings.
The UN report says such acts are "systematic and widespread ... abuses of international human rights law and humanitarian law."
"These acts may, in some instances, amount to war crimes, crimes against humanity, and possibly genocide."