Ukraine resumes blackouts after missiles

"Once the causes of the emergency shutdowns are eliminated, the units will return to operation, which will reduce the deficit in the power system and reduce the amount of restrictions for consumers," it said.

DTEK, Ukraine's biggest private electricity producer, said it would reduce electricity supply by 60 per cent for its consumers in Kyiv where temperatures are hovering around zero degrees Celsius.

Of the remaining supply, only 42 per cent was left over for everyday consumers after critical infrastructure needs were accounted for, it said.

"We are doing everything possible to provide power to every customer for 2-3 hours twice a day," DTEK's Kyiv branch wrote on Facebook.

The national system's power capacity deficit had fallen to 27 per cent, Ukrenergo said.

Moscow says its attacks on vital 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.