Kyiv has vowed to increase its strikes on Russian territory, in particularly on Russia's oil infrastructure, in what it sees as a legitimate response to Moscow's daily barrages of Ukrainian cities and its energy network that have at times cut off heating and power to millions.

Russia's defence ministry sad it had downed 251 Ukrainian drones overnight -- one of the highest daily tolls since Russia launched its offensive in February 2022.

In the Belgorod border region, thousands were left without electricity.

"Currently there is a partial blackout in 24 settlements, affecting 5,400 people," Belgorod Governor Vyacheslav Gladkov said on social media.

A refinery in the southern Krasnodar region was also hit, wounding two people, local authorities said.

Ukraine said Moscow launched 116 drones at its territory, hitting an energy facility in the Chernigiv region and killing one woman in the Kherson region.

Officials in Ukraine say Russia is intensifying its targeting of the country's power grid, repeating a tactic of previous winters that at times left millions without heating or lighting in sub-zero temperatures.

Ukraine's retaliatory strikes on Russia's oil refineries over recent months have triggered fuel shortages in several Russian regions of the country and pushed up petrol prices.

Kyiv aims to cut off vital energy revenues for Moscow that it says fund the Russian army.