Ukrainian President Volodymyr Zelenskyy has accused Russia of engaging in “energy terrorism” after Russian strikes on Ukraine's energy network left millions of residents without power.

About 4.5 million people were without electricity across the country, Zelenskyy said in his nightly address on Thursday.

Kyiv Mayor Vitali Klitschko said 450,000 apartments in the capital alone did not have electricity on Friday.

“I appeal to all residents of the capital: save electricity as much as possible, because the situation remains difficult!” the mayor wrote on Telegram. State-owned grid operator Ukrenergo reported on Friday that emergency blackouts would take place across Kyiv.

Russia has repeatedly carried out missile and drone attacks on Ukrainian power facilities, particularly in recent weeks. In his address, Zelenskyy described the targeting of energy infrastructure as a sign of weakness.

“The very fact that Russia is resorting to energy terrorism shows the weakness of our enemy," he said. “They cannot beat Ukraine on the battlefield, so they try to break our people this way.”

Zelenskyy's spoke soon after Moscow-appointed authorities in southern Ukraine's occupied Kherson region said Russian troops were likely to leave the city of Kherson — a claim that Ukrainian officials greeted with some scepticism.

The Kremlin-installed regional administration already has moved tens of thousands of civilians out of the city, citing the threat of increased shelling as Ukraine's army pursues a counteroffensive to reclaim the region.

Authorities removed the Russian flag from the Kherson administration building on Thursday, a week after the regional government moved out.

Ukraine's southern military spokeswoman, Natalia Humeniuk, said the flag's removal could be a ruse “and we should not hurry to rejoice”. She told Ukrainian television that some Russian military personnel are disguising themselves as civilians.

Neither side's claims could be independently verified.

Elsewhere, Ukrainian officials reported shooting down drones launched by Russian forces. Dnipropetrovsk Gov. Valentyn Reznichenko said eight drones were shot down in the Nikopol area, which was also subjected to artillery shelling.

Another drone was shot down over the western Lviv region, Gov. Maksym Kozytskyy said.

The commander of Ukraine's armed forces, Valeriy Zaluzhny, said on Thursday night that Russian forces had “tripled the intensity of hostilities on certain areas of the front” and were carrying out “up to 80 attacks every day”.

Zelenskyy's office said on Friday that at least nine civilians were killed and 16 wounded in Ukraine over the past 24 hours.

The Russian army attacked four cities close to the Zaporizhzhia Nuclear Power Plant with drones and heavy artillery. Governor of the Dnipropetrovsk province Valentyn Reznichenko said Friday that houses, cars and a gas pipeline had been damaged overnight in Chervonohryhorivka, and that the town was without electricity.

In the eastern Donetsk province, the town of Pokrovsk was the hardest hit, with rocket attacks damaging a school and at least 22 residential buildings, killing one civilian and wounding another six. Donetsk province governor Pavlo Kyrylenko said 12 towns and villages were shelled, including Bakhmut and Avdiivka, which have been particularly hard hit in recent weeks.

In occupied Kherson province, the Ukrainian army shelled Russian bases and logistics facilities, destroying two ammunition warehouses, Ukrainian army officials said.

Russia illegally annexed the Kherson, Donetsk, Luhansk and Zaporizhzhia regions of Ukraine in late September and subsequentally martial law in the four provinces.

The Russian military said it struck the rocket engine manufacturing facilities of a factory in the Dnipropetrovsk province city of Pavlohrad, as well as a factory producing rockets for multiple launch rocket systems in the northeastern city of Kharkiv. Ukraine did not confirm the attacks.

The Ukrainian Armed Forces also said that in the Black Sea, “the functioning of grain corridors continues” according to plan.

Russia agreed on Wednesday to rejoin a wartime agreement brokered by the United Nations and Turkey allowing Ukrainian grain and other commodities to be shipped to world markets.

Moscow had suspended its participation in the grain deal over the weekend, citing an alleged drone attack against its Black Sea fleet in Crimea.

As one condition for returning to the deal, Russia demanded the grain be sent to poorer countries, arguing that most of it was currently ending up in richer nations.

Turkish President Recep Tayyip Erdogan said on Friday he had discussed the issue of prioritising less developed countries for the grain shipments during a call with UN Secretary-General Antonio Guterres.