Volker Türk said he was outraged by renewed overnight attacks that knocked out power and heating in major cities – including Kyiv and Odesa – as temperatures plunged well below zero and civilians bear the brunt of what he described as unlawful assaults on civilian infrastructure.

He said the Russian strikes “can only be described as cruel. They must stop. Targeting civilians and civilian infrastructure is a clear breach of the rules of warfare.”

According to Ukrainian authorities, the latest long-range attacks triggered emergency power and heating outages across several regions.

In Kyiv alone, the city’s mayor reported that 5,635 multi-storey residential buildings were left without heating on Tuesday morning, nearly 80 per cent of which had only recently had heating restored after similar strikes earlier this month.

Since October last year, Russian armed forces have renewed systematic large-scale attacks against Ukraine's energy infrastructure, with strikes recorded in at least 20 regions of the country.

Mr. Türk called on Russian authorities to immediately halt the attacks, warning that continued strikes on essential civilian infrastructure risk compounding human suffering.

Humanitarian consequences

“This means that hundreds of thousands of families are now without heating and several areas, including a significant part of Kyiv, are also without water,” Mr. Türk said, warning that the impact falls most heavily on children, older people and persons with disabilities.

The humanitarian toll was underscored by Matthias Schmale, the UN Humanitarian Coordinator for Ukraine, who said that over the past 48 hours tens of thousands of civilians once again woke to freezing homes and severe disruptions to basic services.

“Parents cannot prepare hot meals for their children, and many older people have been left isolated in cold homes yet again,” he said. “The hideous strikes on energy that have such a huge negative impact on the lives of the civilian population violate international humanitarian law and should end immediately.”

Nuclear safety risks

The attacks have also raised fresh concerns over nuclear safety. The International Atomic Energy Agency (IAEA) said several electrical substations vital for nuclear safety were affected.

Chernobyl Nuclear Power Plant temporarily lost all off-site power, while power lines to other nuclear facilities were also impacted. “The IAEA is actively following developments in order to assess impact on nuclear safety,” Director General Rafael Grossi said.

Chernobyl was the site of the world’s worst nuclear accident in April 1986, when a reactor explosion released massive amounts of radioactive material across Ukraine, Europe and beyond.

Although the plant has long ceased power generation, it requires a stable electricity supply to maintain cooling systems, radiation monitoring and the safe management of nuclear waste, making uninterrupted power critical to preventing new safety risks.