Russian attacks left Ukraine's southeastern regions of Dnipropetrovsk and Zaporizhzhia almost entirely without power, the country's energy ministry said on Wednesday night.


Critical infrastructure was operating on reserve power, it said in a statement on Telegram, while officials said water supplies and the internet were also disrupted.


Russia has recently intensified attacks on Ukraine's energy infrastructure, aimed at paralysing power supplies during a harsh winter.


Ukraine's energy system is under enemy attacks every day, and energy workers are operating in extremely difficult conditions to provide people with light and heat, Ukraine's Prime Minister Yulia Svyrydenko wrote on Telegram.


Deteriorating weather conditions put additional strain on critical infrastructure, she said.


The disruptions to power and heating have come as temperatures plunge.


Emergency restoration work in the regions affected by the attack will begin immediately as soon as the security situation allows, state energy company Ukrenergo said on Telegram.


It added: The primary task of energy workers is to restore critical infrastructure. Dnipro city Mayor Borys Filatov reported on Telegram that all city hospitals had been completely switched to generators.


There are the necessary water supplies; the treatment process does not stop. Water drainage in houses is also supported by alternative power sources, Filatov said.


School holidays had been extended until 9 January because of the power cuts, he added. The head of the Zaporizhzhia regional administration, Ivan Fedorov, said everything possible was being done to restore power.


At this time, water utility workers have almost restored water to our homes, despite the fact that there is a complete blackout in the region, Fedorov said in a video message published on Telegram.


DTEK, Ukraine's biggest private energy provider, is living in permanent crisis mode because of Russian attacks on the grid, its chief executive told the BBC last month, with most of Ukraine suffering from lengthy power cuts during winter.


Maxim Timchenko, CEO of DTEK, which provides power for 5.6 million Ukrainians, mentioned that the frequency of strikes has made recovery difficult.


As the fourth anniversary of Russia's full-scale invasion approaches, Timchenko expressed that Russia has repeatedly targeted DTEK's energy grid with waves of drones, cruise and ballistic missiles and his company has struggled to cope.


The attacks coincide with Ukrainian President Volodymyr Zelensky's statements concerning inadequate guarantees from European allies for protection against new Russian aggression.


Following talks in Paris on Tuesday, the UK and France signed a declaration of intent on deploying troops in Ukraine if a peace deal is reached with Russia. Moscow has warned that any foreign troops in Ukraine would be seen as a legitimate target.