Human rights group Amnesty International accused Ukraine of endangering civilians by basing troops in residential areas during Russia's invasion.
Amnesty staff described seeing Ukrainian forces establishing bases and operating weapons systems in residential areas in the east and south from April to July.
Amnesty International Secretary-General Agn s Callamard called on Ukraine to make sure its forces are located away from populated areas or for all civilians to be evacuated first.
Ukraine denied the claims and reacted angrily, with President Volodymyr Zelenskyy accusing Amnesty of abetting Russia's unprovoked attacks.
In his nightly video address, he said Amnesty was trying to shift the responsibility from the aggressor to the victim. There are no conditions even hypothetically under which any Russian attack on Ukraine becomes justified, he said.
Zelenskyy said the group was trying to amnesty the terrorist state, referencing a term he often uses for Russia.
Ukrainian officials say they take every possible measure to evacuate civilians from frontline areas. Amnesty has previously said there was evidence of Russia committing war crimes by attacking civilians, a claim that Moscow denies.
Ukrainian Deputy Defence Minister Hanna Malyar said that failing to criticise Russia's actions is like studying the actions of the victim without considering the actions of an armed rapist. Foreign Minister Dmytro Kuleba said he was outraged by the claims and urged Amnesty to stop creating a false reality.