By Stephanie Nebehay
GENEVA, Aug 25 (Reuters) - United Nations human rights chief Navi Pillay on Monday condemned "appalling, widespread" crimes being committed by Islamic State forces in Iraq, including killings, slavery, sexual crimes and targeting people on ethnic or religious grounds.
The persecution and systematic violations, documented by U.N. human rights investigators, would amount to crimes against humanity and war crimes under international law, she said in a statement.
"Grave, horrific human rights violations are being committed daily by ISIL and associated armed groups," Pillay said. "They are systematically targeting men, women and children based on their ethnic, religious or sectarian affiliation and are ruthlessly carrying out widespread ethnic and religious cleansing in the areas under their control."
Christians, Yazidis and Turkmen are among those targeted by the Sunni militant group, she said.
Up to 670 prisoners from Badush prison in the city of Mosul were killed by Islamic State on June 10 after being taken by truck to a vacant area and screened for non-Sunnis, she said, quoting survivors and witnesses to the "massacre" as telling U.N. human rights investigators.
"Such cold-blooded, systematic and intentional killings of civilians, after singling them out for their religious affiliation, may amount to war crimes and crimes against humanity," Pillay said.
The al Qaeda splinter group seized control of the Iraqi city of Mosul on June 10, putting security forces to flight in a spectacular show of strength against the Shi'ite-led Baghdad government.
Pillay, a former U.N. war crimes judge, called on the Iraqi government and international community to protect vulnerable ethnic and religious communities, including at least 13,000 Shia Turkmen in Salahuddin province besieged by ISIL forces since mid-June amid "fear of a possible imminent massacre".
(Reporting by Stephanie Nebehay, editing by Ralph Boulton)