Russia on Wednesday, Jan 9 investigated the death of a 27-year-old man in a giant "zorb" ball that tumbled down a mountainside in a horrific accident that was caught on video, AFP reported.

Denis Burakov, 27, died of his injuries after he and a friend, Vladimir Shcherbov, 33, paid to roll together in the zorb down an unfenced snow slope at a ski resort in the Karachayevo-Cherkessia region of the North Caucasus.

"We have launched a criminal case into causing death through providing unsafe services," said Sergei Shuvayev, spokesman for the regional investigative committee. The charge carries a maximum prison sentence of six years.

Zorbing is an extreme adventure sport invented in New Zealand in the 1990s in which participants roll down slopes strapped inside large transparent plastic balls.

Deaths from zorbing accidents are very rare.

During the January 3 accident, the zorb with the two men veered off a snowy track down the 3,000-metre-high Mussa-Achitaro peak and rolled into a gorge, continuing for around a kilometre before stopping on a frozen lake, investigators said.