Iraq witnessed a sharp increase in civilian deaths following the fall of large swaths of territory to the Islamic State in Iraq and Syria group in the summer of 2014. Now despite a string of recent battlefield losses for ISIS, civilians in Iraq continue to die at a "staggering" rate, according to a new United Nations report.

At least 18,802 civilians were killed and another 36,245 were wounded in Iraq between the start of 2014 and Oct. 31 of last year, according to the UN report released Tuesday. In just one six-month period between May and October last year, more than 10,000 civilians were killed.

"Despite their steady losses to pro-government forces, the scourge of ISIL continues to kill, maim and displace Iraqi civilians in the thousands and to cause untold suffering," UN envoy Jan Kubis said in a statement, using an alternative acronym for the extremist group.

The numbers are nowhere near the death tolls recorded during Iraq's bloody civil war. In 2006 alone more than 34,000 civilians were killed, according to UN data.

The following year the Iraqi government refused to provide the UN with death toll statistics, stating that the government wanted to prevent the data from painting a negative image of the country. But civilian casualties since the rise of IS in Iraq are considerably higher than the preceding years of relative stability. In 2011, the number of civilian deaths due to violence was at its lowest since the civil war, with fewer than 2,800 killed.

UN human rights chief Zeid Raad al-Hussein said the civilian death toll may actually be considerably higher.

"Even the obscene casualty figures fail to accurately reflect exactly how terribly civilians are suffering in Iraq," he said in a statement.

Slavery, child abduction documented

The UN report also documented a wide range of human rights abuses, including the ISIS group's conscription of some 3,500 people into slavery. Many of those are women and children from the Yazidi religious minority who were taken hostage in the summer of 2014 and forced into sexual slavery.

It said another 800 to 900 children were abducted from Iraq's second largest city, Mosul, for religious and military training. A number of ISIS child soldiers were killed by the extremists when they tried to flee fighting in the western Anbar province, it said.

"ISIL in particular has used the most gruesome methods to execute people by running bulldozers over them, by burning them alive. In one case, people were put in a cage and the cage was put into the water," Ravina Shamdasani, a UN spokeswoman told The Associated Press in Geneva.

"I think this kind of violence will affect our society for the long term," said veteran Iraqi human rights activist Hana Adwar. "The culture of violence is rooted in Iraq now, it's not something that's easy to combat."

"War crimes"

The UN report called the civilian death toll in Iraq "staggering." It also detailed the various methods the ISIS group has employed to kill its enemies, including public beheadings and throwing them off buildings.

Such acts are "systematic and widespread ... abuses of international human rights law and humanitarian law," the report said. "These acts may, in some instances, amount to war crimes, crimes against humanity, and possibly genocide."

After ISIS was pushed out of the majority Yezidi town of Sinjar a number of assumed burial sites that local officials have dubbed "mass graves" were found in the town.

"They are symbols of a nation, they are symbols of Kurdistan and they represent the victims of terror," said Mahmood Salih Hama Karim, the minister with the Kurdish Regional Government responsible for overseeing excavation of the sites.