President Volodymyr Zelenskiy warned Ukrainians to expect another brutal week of cold and darkness ahead, predicting more Russian attacks on infrastructure which would not stop until Moscow runs out of missiles.

Russia has been launching massive missile bombardments on Ukraine's energy infrastructure roughly weekly since early October, with each attack having greater impact than the last as damage accumulates and winter sets in.

In an overnight address, Zelenskiy said he expected new attacks this week that could be as bad as last week's, the worst yet, which left millions of people with no heat, water or power.

"We understand that the terrorists are planning new strikes. We know this for a fact," Zelenskiy said in his nightly video address on Sunday. "And as long as they have missiles, they, unfortunately, will not calm down."

Kyiv says the attacks, which Russia acknowledges target Ukrainian infrastructure, are intended to harm civilians, making them a war crime. Moscow denies its intent is to hurt civilians but said last week their suffering will not end unless Ukraine yields to Russia's demands, without spelling them out.

In Kyiv, snow fell and temperatures hovered around freezing on Sunday as millions in and around the Ukrainian capital struggled with disruptions to electricity supply and central heating caused by the waves of Russian air strikes.