Kangaroo courts set up by the retreating militants of the Islamic State(ISIS) ordered the killing of 40 civilians in Mosul, Iraq. Bodies of the victims were thereafter hung on power poles, the United Nations said today.

In a statement outlining human rights abuses committed by the militant group also identified as Daesh, ISIS and ISIL in Iraq, U.N. High Commissioner for Human Rights Zeid Ra’ad Al Hussein reported killings of civilians based upon decisions by self-appointed IS courts.

“On Tuesday, ISIL reportedly shot and killed 40 civilians in Mosul city after accusing them of ‘treason and collaboration’ with the Iraqi security forces. The victims were dressed in orange clothes marked in red with the words ‘traitors and agents of the ISF.’ Their bodies were then hung on electrical poles in several areas in Mosul city.”

The statement detailed other atrocities allegedly committed by IS as Iraqi forces attempt to take back control of the city, which has been under IS control for the past two years.

The operation to retake the city involves 50,000 Iraqi security forces personnel, including soldiers, police, Kurdish Peshmerga fighters, Sunni Arab tribesmen and Shiite militiamen, the BBC reported.

The U.N. statement reported a man was shot to death for ignoring an IS ban on use of mobile phones.

Six civilians also were hanged for carrying banned SIM cards, a data storage element of cellphones; 20 civilians shot to death on charges of leaking information; and boys that IS calls “sons of the caliphate” were deployed to roam the streets of Mosul wearing explosive belts.

An underground IS prison holding 961 starving inmates was found; IS is also abducting women and relocating them to Mosul, and has a fleet of loudspeaker-equipped vehicles which announce anyone escaping battles with the Iraqi security Forces will be executed, the UN statement says.