Russia attacked Ukraine's energy system and some cities with cruise and ballistic missiles plus drones on Wednesday in an "inhuman" Christmas Day assault, Ukraine's President Volodymyr Zelenskiy said.

Nearly three years into the war, the strikes wounded at least six people in the northeastern city of Kharkiv and killed one in the region of Dnipropetrovsk, the governors there said.

Half a million people in Kharkiv region were left without heating, in temperatures just a few degrees Celsius above zero, while there were blackouts in the capital Kyiv and elsewhere.

"Today, (Russian President Vladimir) Putin deliberately chose Christmas to attack. What could be more inhuman? More than 70 missiles, including ballistic missiles, and more than a hundred attack drones," he said.

Ukraine's military said its air defences downed 59 Russian missiles and 54 drones overnight and on Wednesday morning.

Ukrainians were marking their second Christmas on Wednesday, according to a new calendar in another step towards erasing Russian influence.

Most Ukrainians are Orthodox Christians and the independent Orthodox Church of Ukraine, set up in 2018, agreed in 2023 to move away from the traditional Julian calendar used in Russia where Christmas is Jan. 7.

Russia has intensified attacks on the Ukrainian energy sector since spring of this year, damaging almost half of its generating capacity and causing prolonged blackouts.

'Russia weaponizes winter'

Ukraine's air force said Kharkiv was attacked by ballistic missiles. Regional governor Oleh Syniehubov said on Telegram there was damage to civilian non-residential infrastructure, without giving more detail.

Dnipropetrovsk Governor Serhiy Lysak said the fatality there occurred in an attack on regional power facilities.

"Since the morning, the Russian army has been massively attacking the Dnipro region. It is trying to destroy the region's power system," he said.

Ukraine's Energy Minister German Galushchenko said on Facebook that Russia was massively attacking the power sector and that restrictions on electricity supply were in place.

Ukraine's largest private energy company DTEK said its generating facilities were attacked, with power equipment seriously damaged, in the 13th large-scale assault on the energy sector this year.

"We appeal to every ally of Ukraine to end this state-sponsored terrorism now by giving our armed forces the air defence ammunition they need to protect essential energy infrastructure," DTEK CEO Maxim Timchenko said in a statement.

There was no comment from Russia on the attacks.

"Russia’s Christmas gift to Ukraine: more than 70 missiles and 100 drones, directed at Ukrainian families celebrating in their homes and the energy infrastructure that keeps them said U.S. ambassador Bridget Brink.

"For the third holiday season, Russia weaponizes winter."