North Korean troops deployed in Russia's Kursk region are suffering heavy losses and being left unprotected by the Russian forces they are fighting alongside, Ukrainian President Volodymyr Zelenskiy said on Friday.

Ukraine's military intelligence said Ukrainian strikes near Novoivanovka inflicted heavy casualties on North Korean units. It said North Korean troops also faced supply issues and even shortages of drinking water.

Ukraine's air force says it detected 184 missiles and drones, causing damage to energy infrastructure across the country.

A large-scale Russian missile and drone attack targeting Ukraine ’s energy system on Christmas Day has been condemned as “inhumane” by president Volodymyr Zelensky. Half a million people were left without heating in Kharkiv in temperatures just a few degrees above freezing, as blackouts were reported in Kyiv and other regions.

Russia attacked Ukraine's energy system and some cities with cruise and ballistic missiles plus drones, Ukraine's President Volodymyr Zelenskiy said.