Russia has released footage of the world’s largest ever nuclear explosion.

Until now, footage and details of the bomb were very limited and most was kept secret.

A 40-minute video of previously classified material was released earlier this month by the Russia’s state-run nuclear division ROSATOM.

The name of the bomb was the Tsar Bomb and it was 3,333 times more powerful than the bomb that was dropped on Hiroshima, Japan. The hydrogen bomb was 50 million tons.

The device was detonated on 30 October 1961 off the coast of Severny Island near the Arctic Ocean off a the Tu-95V bomber.

The explosion was so powerful that the bomber was hit by the bomb’s shock-wave even though being 75 miles away and the mushroom cloud stretched 42 miles into the air meaning seven times higher than Mount Everest, and reports claim it destroyed buildings 55km of it.

The Tsar bomb was one of the last above ground nuclear tests done as the US, UK and Soviet Union signed a deal in 1963 which banned such tests.