Nearly half a million households were left without power on Christmas Day in frigid weather after further missile attacks by Russia on Ukraine's damaged power grid, according to multiple reports.

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.

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