President Volodymyr Zelenskiy said Russia launched more than 450 drones and 45 missiles in overnight attacks on Ukraine.
Three people were killed and 12 wounded in the city of Dnipro when a drone hit an apartment building. Three were killed in southeastern Zaporizhzhia region and one in Kharkiv region farther north, regional officials said. Energy facilities in the Kyiv, Poltava and Kharkiv regions were damaged, Prime Minister Yulia Svyrydenko said.
Energy Minister Svitlana Hrynchuk said emergency crews had stabilised the power grid, but warned consumers further power cuts were needed to allow work to proceed after the attacks.
"We first introduced emergency power cuts ... and then moved to hour-long cuts. We then managed to more or less stabilise the system," Hrynchuk said on national television.
"We are assessing the aftermath and co-ordinating what actions to take in order to find alternative power sources to ensure people get their power and heating back."
News reports and unofficial social media accounts said blackouts persisted in at least two regions - Kharkiv in the northeast and Poltava in central Ukraine.
State-owned energy company Tsentrenergo said the attacks were the largest on its facilities since the start of the war in February 2022, and that it had halted operations at its plants in the Kyiv and Kharkiv regions.
"The last strike was not even a month ago and the enemy has now struck all our generating capacity at the same time. The stations are on fire!" Tsentrenergo, which generates about eight per cent of Ukraine's power, said in a statement.
"Our generation is now zero."
Zelenskiy said sanctions pressure should be intensified.
"For every Moscow strike on energy infrastructure - aimed at harming ordinary people before winter - there must be a sanctions response targeting all Russian energy, with no exceptions," he said on the Telegram app.
Since the start of its invasion almost four years ago, Russia has made a point of attacking the power sector as the need for heating grows. This northern autumn, it has attacked gas facilities nine times within two months, according to the state firm Naftogaz.
Moscow's Defence Ministry said it had launched "a massive strike with high-precision long-range air, ground and sea-based weapons" on weapon production and energy facilities in response to Kyiv's strikes on Russia.
Russia also said its forces continued to advance in grinding battles around the towns of Pokrovsk and Kupiansk, and had captured a tiny village in eastern Ukraine.
Ukraine regularly sends drones to strike oil facilities inside Russia.
As diplomatic peace efforts have faltered, Kyiv is trying to reduce Moscow's ability to finance its war.
The Ukrainian air force said 406 Russian drones and nine missiles had been shot down, and 26 Russian missiles and 52 drones had hit 25 sites. Svyrydenko said the government and energy companies were working to restore damaged electricity, water and heating provision.
In the Poltava region, two cities - Kremenchuk with a population of about 200,000 people and Horishni Plavni with 50,000 - lost most of their electricity and were using generators to provide water, city officials said.
with DPA
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