More than 500 Ukrainian localities remained without power Sunday following weeks of Russian airstrikes on the electric grid, an interior ministry official said.

"The enemy continues to attack the country's essential infrastructure. Currently, 507 localities in eight regions of our country are cut off from electricity supplies," deputy interior minister Yevgueny Yenin told Ukrainian television.

"The Kharkiv region is the worst hit with 112 isolated villages," Yenin added.

Another 90 villages were cut off in the Donetsk and Kherson regions, he said, with others in the regions of Mykolaiv, Zaporizhzhia and Lugansk.

On Saturday, Ukrainian authorities -- including Mykolaiv region governor Vitali Kim -- had once again urged civilians to bear up in the face of continually deteriorating early winter conditions and regular power outages.

Repeated daily power cuts have left millions of people without heat or lighting while outside temperatures have dropped below zero Celsius (32 Fahrenheit) in recent days.

With further strikes on the network widely expected, Ukrainians fear a difficult prolonged winter as well as a flood of departures by refugees from a war now into a tenth month.

Private Ukrainian energy operator DTEK said Thursday that nearly half of Ukraine's electricity grid remains damaged after Russia began targeting Ukrainian energy facilities in October following a series of humiliating military defeats on the ground.