Huge blast hits major Russian oil refinery

A huge explosion has badly damaged a key oil refinery in far eastern Russia in just the latest mystery blast to hit the country's infrastructure.

The blast struck Angarsk Oil Refinery, near the Siberian city of Irkutsk, around 5.50 am local time on December 15 - lighting up the early morning sky with a fireball, Daily Mail reports.

Two people were killed and five injured in the explosion, which officials say was caused by "gas contamination" of the plant's equipment though it is unclear whether this was an accident or whether it was sabotaged.

It comes against the backdrop of multiple blasts and fires at locations with links to Russia's military or oligarchs that many suspects are being orchestrated by Ukraine.