Russia launched aerial attacks on Ukraine’s energy sector “on a massive scale” overnight into Wednesday, local authorities said, with explosions reported across the country amid intensified bombardments that have left Ukraine in a precarious position while the war grinds into a third winter.

Russia attacked Ukraine's energy system and some cities in an "inhuman" Christmas Day assault, Ukraine's President Volodymyr Zelenskyy said.

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

An Azerbaijan Airlines plane crash on Christmas Day has prompted speculation the plane was shot down by Russia after it took a detour of hundreds of miles in the wrong direction and crash-landed with holes in the fuselage.

The flight was en route from the Azerbaijani capital of Baku to Grozny, in Russia’s south, when it diverted and attempted an emergency landing in Kazakhstan.

Officials in Russia and Kazakhstan are urging people to wait for an investigation into the deadly Azerbaijan Airlines plane crash before assigning blame.