The top secret memos appear to back up conspiracy theories that extra-terrestrials landed in the US town of Roswell - before they were sent to the infamous Area 51 US airbase.
Three circular-shaped spaceships crashed containing the bodies of extra-terrestrials which were only three feet tall, said a special agent in 1950.
The explosive claims - that could be out of an episode of sci-fi thriller X Files - were unearthed after classified FBI documents were made public.
And they are sure to fuel conspiracy theorists' beliefs that the existence of alien life has been covered up.
Last night UFO experts said the files could be final proof that aliens and flying saucers "are real".
The amazing UFO find at Roswell, New Mexico, was detailed by FBI agent Guy Hottel in a 1950 memo to the agency's director.
Hottel reveals what a US Air Force investigator found.
"Three so-called flying saucers had been recovered in New Mexico.
"They were described as being circular in shape with raised centers, approximately 50ft in diameter.
"Each one was occupied by three bodies of human shape but only 3ft tall dressed in a metallic cloth of a very fine texture.
"Each body was bandaged in a manner similar to the blackout suits used by speed flyers and test pilots."
The name of the investigator who told Hottel about the sensational discovery has been blacked out in the memo titled 'Flying Saucers' and there is no mention of the date of the discovery.
Roswell's radar sparked technical problems on the UFOs causing them to come down, said Hottel who was in charge of the FBI's Washington field office.
