The U.N. High Commissioner for Human Rights Volker Turk said on Thursday that further strikes on Ukraine's infrastructure could lead to a serious deterioration of the humanitarian situation and spark further displacement.
Russia's attacks on Ukraine's electricity infrastructure have left millions of people without heat, clean water or electricity as temperatures plummet and some 18 million people now rely on humanitarian aid.
Moscow says the assaults do not target civilians and are meant to reduce Ukraine's ability to fight and push it to negotiate. Kyiv says the attacks are a war crime.
In a speech to the Human Rights Council following a trip to Ukraine last week, Turk said that Russian strikes were exposing millions of people to "extreme hardship".
"Additional strikes could lead to a further serious deterioration in the humanitarian situation and spark more displacement," he said. He called the war an "unmitigated tragedy and disaster."
Turk was addressing the council to formally present a report which found Russian forces killed at least 441 civilians in the early days of the invasion. Moscow has repeatedly denied targeting civilians in what it calls a "special military operation" in Ukraine.
Turk said accountability for such incidents was "sorely lacking", saying his office has been unable to identify a single case where a member of Russia's armed forces was held accountable by Moscow for carrying out, or failing to prevent, these killings.
Russia, which was suspended from the Geneva-based body earlier this year but can still join discussions, left its seat empty at the meeting. Its diplomatic mission in Geneva did not immediately respond to a request for comment.
(Reporting by Emma Farge; Editing by Madeline Chambers, Alexandra Hudson)