In the eastern Donetsk region, meanwhile, Russian cluster munitions and glide bombs killed four civilians and wounded four more in separate attacks, the regional governor said.

Targeted missile and drone attacks over recent months have crippled Ukraine's electricity generation capacity, and forced Kyiv to impose blackouts and import supplies from European Union states.

"The enemy attacked a number of energy infrastructure facilities," the energy ministry said, adding that the Russian projectiles targeted sites in four regions, including near Kyiv.

AFP journalists in the capital heard air raid sirens ringing out over Kyiv in the early hours of Thursday.

The largest private energy company in Ukraine, DTEK, said the attacks caused "serious damage" at one of its plants, without disclosing its location.

"This is already the seventh mass attack on the company's thermal power plant in the last three months," the company said.

President Volodymyr Zelensky has said that those barrages had halved generation capacity in the war-battered country compared to one year ago.

He has urged Ukraine's allies to send more air defence systems to protect the country's vital infrastructure.

- 'Crisis this winter' -

DTEK's CEO Maxim Timchenko echoed the calls for more military aid, and said the power plant struck early on Thursday had already been damaged in a previous attack.

"We urgently need to close our skies or Ukraine faces a serious crisis this winter. My plea to allies is to help us defend our energy system and rebuild in time," he said.

There was no immediate comment from the Kremlin on the latest barrage but Moscow says its forces do not target civilian infrastructure.

The Russian defence ministry, however, confirmed it had carried out "precision" strikes on energy facilities that support military production, as a response to Ukrainian drone attacks on Russian oil facilities.

In the latest Ukrainian attack on Russian territory, the governor of the Krasnodar region -- near Ukraine's Russian-occupied Crimean peninsula -- announced that one woman had been killed in a drone attack targeting oil facilities.

Among the areas struck was the city of Slavyansk-on-Kuban in the Krasnodar region, where the woman was killed, governor Venyamin Kondratyev said.

The Russian defence ministry said it had downed 15 Ukrainian drones that also targeted oil storage depots in the southern Adygea republic and in the Tambov region.

A source in the Ukrainian security services told AFP drones deployed by the Security Services of Ukraine (SBU) were behind attacks in the two Russian regions.

"These facilities processed and stored raw materials and finished products, which were later used by the Russian army," the source said, vowing more attacks on Russian oil facilities, with the aim of denting the Kremlin's war chest.

- 'Critical infrastructure' -

The Ukrainian air force said that Russia had launched nine missiles and 27 Iranian-designed attack drones, and that air defence systems had downed all the projectiles except four missiles.

It said air defence systems were also activated in the regions of Zaporizhzhia, Donetsk, Kherson, Kharkiv and Kyiv, among others.

The energy ministry said a total of seven employees at energy facilities had been wounded and that more than 200,000 people had been temporarily cut off in the Vinnytsia region.

"There will be no outages for critical infrastructure companies," it added.

Russia has meanwhile stepped up fatal artillery attacks on embattled frontline regions in the south and east of Ukraine.

The governor of the southern Kherson region announced on Thursday morning that two people had been killed and three wounded in recent Russian attacks.

In Kharkiv, a northeastern region where Russia recently launched a surprise ground offensive, the governor said one woman had been killed by Russian fire.

And in the Donetsk region, the governor said two people had been killed earlier, including one in the frontline town of Toretsk, where Russian forces have gained ground after a long lull in fighting there.

The Ukrainian military said Russian forces were trying to dislodge its troops from the nearby villages of Shumy and New York.