The UN has warned of an "alarming deterioration" in human rights in eastern Ukraine, where separatists are fighting security forces.
It also found "serious problems" of harassment and persecution of ethnic Tatars in Crimea, the mainly ethnic Russian region Moscow annexed in March.
Russia condemned the report, saying it ignored abuses by Ukraine's government.
Violence between separatists and pro-Ukrainian forces has left dozens dead in the east and south this month.
Separatists control towns in the Donetsk and Luhansk regions, where they have been skirmishing with units of the Ukrainian security forces, sent in to reassert government control.
The revolt in the east gained momentum after Russia annexed Ukraine's mainly ethnic Russian region of Crimea in March.
Moscow acted after the overthrow of Ukraine's elected pro-Russian President, Viktor Yanukovych, during unrest in the capital Kiev in February, and his replacement with an interim government, backed by Ukrainian nationalists.