The papers, which were written between 2007 and 2012, said “metals unknown to science” had been recovered, tested, and placed into a private facility.
Ufologists had long believed the metals had been taken from an alien crash sites, such as the infamous Roswell incident back in the 1940s.
But, it has sensationally been claimed the Department of Defence spent some of its £16 million UFO budget to contract Bigelow Aerospace in Las Vegas.
James Oberg, a former NASA employee, said he understood the metal had not been recovered and stored by the army or US government, but UFO hunters.
He added: “The money went out of the DoD to Robert Bigelow and he contracted the work out to some UFO groups to look for UFOs and who spent a lot of money retrofitting his buildings to store this material.”
Nick Pope, a former investigator of UFOs for the British Ministry of Defence also believes the parts may have been taken by UFO groups, which investigates alien activities and keeps a database of sightings.