The UNAMI and the Human Rights Office said in a report that from six to 12,000 bodies are estimated in those deposits found in the governorates of Nineveh, Kirkuk, Salah al-Din and Anbar, among others.
It is believed that the common grave of Khasfa in southern Mosul is the biggest one with about 4,000 remains.
So far, only about 28 tanks have been excavated and 1,258 corpses have been exhumed.
The dead include women, children, the elderly and disabled, as well as military and police agents.
From June 2014 to December 2017, the Islamic State occupied almost a third of the entire Iraq territory and during that period, it led a campaign of torture, persecution and assassinations.
These actions are included as crimes of war, crimes against humanity and genocide, the UN report highlights stating that about 33,000 civilians have been executed by the extremist group.
Baghdad, Nov 6 (Prensa Latina) More than 200 mass graves with remains of 1,000 people were detected in Iraq, according to a report from the UN Assistance Mission for Iraq (UNAMI), released today.