The UN's top human rights official said "grave, horrific human rights violations are being committed daily" by the Islamic State group and other fighters allied with it in an aggressive push to gain a firm grip on the northern and eastern provinces.
The group's violations as it expands the boundaries of its self-proclaimed caliphate along the Syria-Iraq border include targeted killings, forced conversions, abductions, trafficking, slavery, sexual abuse, destruction of places of religious and cultural significance, and besieging entire communities for ethnic, religious or sectarian reasons, Pillay said.
Pillay cited the killing of hundreds of Yazidis in Nineveh and up to 2,500 kidnapped at the beginning of August, and the killing and abduction of hundreds of Yazidis in Cotcho village in Southern Sinjar on August 15. She also pointed to at least 13,000 Shia Turkmen in the town of Amirli, including 10,000 women and children, who have been besieged since June 15.
According to the accounts, gunmen then yelled insults at the remaining prisoners, lined them up in four rows, ordered them to kneel and opened fire, reportedly killing up to 670 prisoners.