The attacks on some of Ukraine’s most important population centres, which reportedly involved almost 400 drones, also left thousands without electricity, heating and water.

Temperatures in the country have dropped to -20° Celsius, and the attacks on energy infrastructure have left families in freezing conditions. Many older persons and people with disabilities are often stuck in their homes in high-rise apartment buildings, without electricity and heating, unable to cook hot meals or recharge their devices to stay connected.

The latest attacks took place during ongoing peace talks in the United Arab Emirates, involving delegates from Russia, Ukraine and the United States

In Kharkiv, a dormitory housing displaced persons who fled the fighting on the front line came under fire. A hospital and residential buildings were also damaged.

In the capital, Kyiv, thousands of apartment buildings which were gradually being reconnected to basic utilities after the previous wave of attacks on January 9 and 20, were again left without electricity in sub-zero temperatures.

The entire city of Chernihiv and hundreds of thousands of families in the surrounding region were left without electricity.

Repair crews and humanitarian workers continue to work in low temperatures to help the victims.

According to media reports, more than one million people are without power across the country, around 800,000 of whom are in Kyiv.

"This systematic cycle of attacks on energy infrastructure violates international humanitarian law and must stop," said Mr. Schmale, the Humanitarian Coordinator said in a statement. Ukrainian civilians, he said, should live in their homes in safety and warmth, and not in fear of the next round of destruction.