Last year the 18 files were sent to the National Archives for release to the public, but then mysteriously sent back to the MoD for further censure.
The latest release date was set to be this March, but, again they failed to materialise.
Now, the National Archives has blamed the upcoming general election – called to give Theresa May a mandate for Brexit – for further delays, according to Grenzwissenschaft-Aktuell.de.
They are believed to date from 1971-76 and 1996-2000, and 2004.
It is also hoped there are further files from the December 1980 Rendlesham Forest UFO incident that will shed more light on the bizarre case, when US military officer claim to have seen a UFO land.
The delay to the release of the UFO files has led to cover-up claims.
He said: “Due to the upcoming election here in the UK and the rules relating to government departments during the pre-election period, the files will not be released until after the election.
“We are working to ensure that the files are ready for release as soon after this period as is possible: hopefully around the middle of June.”
In 2013, the MoD claimed to have released all of its UFO related formerly classified files, after beginning declassification in 2008, but it later emerged in 2014 it had held back the 18 still to be released.
UFO hunters hope the files will hold smoking gun evidence of alien visitations.
I understand people’s frustration and can see why this delay is generating conspiracy theories. I hope the release of the last files can be fast-tracked after the election.
In a blog about the delay, Andreas Müller, editor of Grenzwissenschaft-Aktuell.de, wrote: “Since it became known in Autumn of 2014 that contrary to the claim that the British Ministry of Defence (MoD) has released all of its formerly secret UFO-files already back in 2013, still 18 files of the MoD’s former UFO-Bureau files were held back.
“UFO-researches as well as historians look forward to the release of those files, that has been postponed repeatedly since then.
“As even the latest release date given – March 2017 – has passed.”
“When I made the official announcement of the declassification and release of these UFO files in May 2008, the thinking was the the release project would take two or three years.
“Now, over nine years later, I understand people’s frustration and can see why this delay is generating conspiracy theories.
“I hope the release of the last files can be fast-tracked after the election.”