Ukrainian forces and Russian-backed separatists have detained and abused people "with complete impunity", according to Human Rights Watch and Amnesty International.
Wednesday in Kyiv, the groups repeated concerns voiced in a joint report released last year documenting arbitrary, prolonged, and occasionally secret detentions. The rights watchdogs say they have seen "no positive developments" regarding the abuses documented in the July report.
At least nine cases of Ukrainian authorities detaining civilians accused of coordinating with Russian-backed separatists were cited, and nine more of separatist forces detaining civilians suspected of spying for the Ukrainian government.
The human rights organizations say they suspect the number of such detentions is much higher than they are able to document.
"Torture and secret detention ... are taking place right now, on both sides of the conflict," said Denis Krivosheev, deputy director for Europe and Central Asia at Amnesty International. "Those countries providing support, to whatever side, know this perfectly well. They must not continue to turn a blind-eye to these abhorrent abuses."
In the West, Russia is largely seen as having fomented and supported the unrest in eastern Ukraine as retribution for mass protests in Kyiv, which in February of 2014 toppled a pro-Moscow president. Russia denies any official involvement.