Ukrainian President Volodymyr Zelenskyy has said the number of people without power has been halved since the immediate aftermath of Russia's assault this week, but some six million are still cut off.
In his nightly video address, he pleaded with Ukrainians to use energy sparingly. "If there is electricity, this doesn't mean you can turn on several powerful electrical appliances at once," he said.
The authorities on Friday gradually restored power on Friday, aided by the reconnection of the country's four nuclear plants.
But the Russian attacks earlier in the week caused the worst damage so far in the conflict, leaving millions of people with no light, water or heat even as temperatures fell below zero.
National power grid operator Ukrenergo said several hours earlier that 30% of electricity supplies were still out, and asked people to cut back on their energy use. "Repairs crews are working around the clock," it said in a statement on Telegram.
Zelenskyy went to the town of Vyshhorod just north of Kyiv on Friday to look at a four-storey building damaged by a Russian missile. He also visited one of the many emergency centres that have been set up to provide heat, water, electricity and mobile communications.
"Together we will be able to go through this difficult path for our country. We will overcome all challenges and we will definitely win," he said earlier.
Moscow says the attacks on basic infrastructure are militarily legitimate, and that Kyiv can end the suffering of its people if it yields to Russian demands. Ukraine says attacks intended to cause civilian misery are a war crime.
The European Union will step up efforts to provide Ukraine with support to restore and maintain power and heating, European Commission President
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