The shocking report, which includes claims that 23 soldiers were turned into stone by the aliens in the UFO after they transformed into a ball of light, was buried among thousands of declassified files published online by the US intelligence agency.

The report in question, created on March 27 1993, is a translation by the CIA of a report from the Ukrainian newspaper Ternopil vechirniy.

The newspaper report said that after Mikhail Gorbachev lost power in 1991, many KGB files made their way to the CIA, including an alleged 250-page dossier on the bizarre UFO attack, which included pictures and witness testimonies.

The report suggested that a low flying flying saucer had appeared over a military unit in training in Siberia, before one of the soldiers fired a surface to air missile, bringing it down.