REUTERS

"Prisoners on both sides have been beaten and subjected to mock executions. We have also documented summary killings of those held by separatist groups. It is a war crime to torture or deliberately kill captives taken during conflict."

"Pro-Kyiv and separatist forces alike must put an end to these crimes and ensure that all fighters under their control are aware of the consequences under international law of abusing prisoners amid an armed conflict. The Ukrainian authorities must investigate all allegations of war crimes and other abuses, open files and collect evidence of abuses by separatist forces and bring to justice all those responsible for perpetrating such heinous acts."

Out of 33 former prisoners interviewed by Amnesty International, 32 described severe beatings or other serious abuse being meted out by separatist and pro-Kyiv groups alike. All of them were held captive at some point between July 2014 and April 2015, and the organization conducted most of the interviews in March, April and May of this year.