More than two thirds of the Ukrainian capital was still without power on Thursday morning and a swathe of residents had no running water, a day after Russian missile strikes caused Kyiv's biggest outages in nine months of war.
Energy Minister German Galushchenko said three nuclear power stations that were switched off because of the attacks on Wednesday were expected to be back on line later on Thursday, and this would help ease supply problems.
"The situation is difficult throughout the country," he said in televised comments, adding that power generation would gradually increase throughout the day.
Kyiv was one of the main targets of Wednesday's attacks on energy facilities that cut power in many regions and made emergency blackouts necessary in others to conserve energy and enable repairs as winter sets in.
The temperature plunged below zero degrees Celsius overnight in a city that had 2.8 million residents before the war and where it has already snowed and the streets are icy.
Kyiv Mayor Vitali Klitschko said electricians and repair workers were doing everything to get the power back on "as fast as possible" but the recovery would depend largely on the overall energy "balance" of the nationwide grid.
Kyrylo Tymoshenko, deputy chief of President Volodymyr Zelenskiy's staff, said power supplies had been restored in the Kirovohrad and Vinnytsia regions.
Power was also largely back in the northern region of Sumy, and 3,000 miners who had been trapped underground during a power outage had been brought to the surface in central Ukraine, regional officials said.
In the south, Mykolaiv region governor Vitali Kim appealed to Ukrainians to be as frugal as possible in their use of power.
"Consumption has been growing this morning (which is logical), there isn't enough capacity in the system to switch it on for more consumers!!," he wrote on the Telegram messaging app."The energy system is united like we all are! If you've turned off a few unneeded lights, that's really important!!!"