Both the Islamic State militants and the Iraqi government forces are guilty of committing war crimes in the three months of fighting, the UN said in a report adding that the Islamic State militants have carried out atrocities on "an unimaginable scale".
The UN Deputy High Commissioner for Human Rights, Flavia Pansieri, who opened an emergency debate on Monday, said there was "strong evidence" that Islamic State has carried out numerous atrocities including killings, beheadings, torture, sexual abuse and forced conversions.
"The reports we have received reveal acts of inhumanity to an unimaginable scale. Systematic and intentional attacks on civilians may constitute war crimes and crimes against humanity. Individuals, including commanders, are responsible for these acts," she said.
Iraqi government forces had also committed acts that may amount to war crimes, she added although Reuters later cited her as saying that they were not on the scale of the atrocities carried out by the Islamic State.
The UN, after the meeting, agreed to send a commission to the country to investigate these war crimes according to reports.
Pansieri in her comments added that she was particularly concerned with the persecution of Iraq's religious minorities including the Shia, Yazidis, Christians and Turkmen.
"These communities have lived side by side, on the same soil, for centuries and in some cases for millennia," she said stressing that the militants had carried out ethnic and religious cleansing.
Iraqi police have also executed detainees in Tal Afar while government-allied militias opened fire on a mosque in Khanaqin district killing 73 men, she further said adding that soldiers have carried out many air strikes and shelling in various places killing dozens of civilians.
Iraq's Human Rights Minister Mohammed Shia' Al Sundani, also speaking in the session, stressed that the hardliner jihadist group was threatening to change the very shape of the country.
"The land of ancient Babylon is subjected to threats starting to its very independence, they are attempting to change its demographic and cultural composition," he said adding that the militant group was a problem to the whole world.
"It is a trans-national phenomenon that poses an imminent danger to all countries of the world; it defies all human rights principles and international law."
The US ambassador to the rights forum, Stephen Harper later said: "The stories that have emerged from ISIL's bloody assault on Iraq are the ones of nightmares. Christians and others have been driven from their homes with the threat of 'convert of die'."