The southern Ukrainian city of Kherson, which has been under persistent Russian shelling, has no electricity supply while repair work is carried out, regional officials said Wednesday.

Anxiety is growing in Ukraine after a wave of Russian strikes against the country's power grid threatens to leave towns and cities in the cold and dark during winter.

"Currently, the neighbouring region is repairing the power grids that supply Kherson and part of the (Kherson) region," Kherson governor Oleksandr Prokudin said.

"Power engineers assure us that they will restore electricity in the city within a few hours."

Electricity supplies were also down in parts of the neighbouring Mykolaiv region, which has been coming under heavier Russian bombardments, said the authorities. The immediate cause was a technical failure rather than a strike.

The Ukrainian airforce said separately that Russia had launched 136 Iranian-designed attack drones at Ukraine, but that air-defence systems had shot down 51 and another 60 had been downed by electronic interference defences.