Russia hits Ukraine power plant

Russia pummelled a power plant early Tuesday as it kept up pressure on Ukraine's battered energy system, while unidentified drones hit two oil tankers in the Black Sea.

Four people were killed in Ukraine as Russia fired more than two dozen missiles and hundreds of drones overnight. Moscow has hit Ukraine with daily drone and missile barrages in recent months, targeting energy infrastructure and cutting power and heating in the frigid depths of winter.

Meanwhile, two Greek-owned oil tankers were hit in the Black Sea on Tuesday, one of which was scheduled to load Kazakh oil on Russia's coast, officials said.

Ukraine, which has repeatedly struck Russia's energy sector in retaliation for its neighbour's invasion, did not immediately comment.

The two tankers, the Maltese-flagged "Matilda" and Liberian-flagged "Delta Harmony", did not sustain major damage, an official from Greece's maritime ministry told AFP.

The Matilda was headed to load Kazakh oil at the Caspian Pipeline Consortium (CPC) terminal near Russia's Black Sea port of Novorossiysk when it was attacked, Kazakh state energy firm Kazmunaygas said.

"There were no injuries among the crew. According to preliminary assessments, the vessel remains seaworthy, and there are no signs of serious structural damage," it added. The Delta Harmony's oil tanks were empty at the time of the attack, the Kazakh energy ministry said.

Air defence call

The Russian attacks earlier Tuesday that killed four people targeted the eastern Kharkiv region, where an AFP reporter saw firefighters battling a fire at a postal hub and rescue workers helping survivors by lamp light in freezing temperatures.

Andriy Pidnebesny, a manager at the postal facility, said he was knocked down by the blast wave and tried -- but failed -- to free several colleagues still alive under the rubble.

President Volodymyr Zelensky said "several hundred thousand" households near Kyiv were without power after the strikes, and again called on allies to bolster his country's air defence systems.

"The world can respond to this Russian terror with new assistance packages for Ukraine," Zelensky wrote on social media.

"Russia must come to learn that cold will not help it win the war," he added.