U.N. report includes photos and videos of abuse , victims ' accounts . Panel says actions by ISIS amount to war crimes and crimes against humanity . Children have had fingers amputated for smoking , the report says . Children are also exposed to horrific sights , such as public executions , public mutilations and the display of bodies in town squares and other visible spots , it said . ISIS leaders should be held accountable by an international court , paper says .
U.N. report includes photos and videos of abuse , victims ' accounts . Panel says actions by ISIS amount to war crimes and crimes against humanity . Children have had fingers amputated for smoking , the report says . ISIS leaders should be held accountable by an international court , paper says .