The major boost for alien hunters can be exclusively revealed by Express.co.uk on World UFO Day, which campaigners are using to call for the release of all such records globally.
UFO researchers, backed by House of Lords peer, have been fighting for the release of 18 top secret Ministry of Defence (MoD) files about UFO sightings from more than 30 years ago.
The Government faced claims of a cover-up from conspiracy theorists when their release was stalled at the end of 2013.
Some investigators claim the files could provide key evidence of extra-terrestrial life visiting the UK and of specific information about famous controversial sightings such as the Rendlesham Forest incident – a series of reported sightings of unexplained lights and the alleged landing of one or more craft in Suffolk in late December 1980.
Lord Black of Brentwood, who asked the Government for an update through a Parliamentary question, was assured yesterday – the day before World UFO day – the files would be released by the MoD to the National Archives by March next year.
Alien hunters are confident these records could prove if extra-terrestrial life actually exists, as these were the most secretive files held in the private offices of various Cabinet ministers.
Although the files are being released to the National Archives, it is not yet clear when they will be available for public inspection.
In his Parliamentary question, Lord Black asked: "In relation to the 18 Ministry of Defence files on unidentified aerial phenomena (UAP) that have yet to be released to the public, what is the originating division of the file reference M9/18; what is the remit of that division in relation to UAP; and what is their latest estimate of when the 18 files will be passed to the National Archives, and then released to the public."
Defence Minister Earl Howe replied: "The originating branch of file reference MO9/18 relates to ministers' private offices. The latest estimate of when the 18 files will be delivered to the National Archives is before March 2016.
"The National Archives will make the necessary judgement about when they release these files to the public."
A number of older UFO files held by the UK government have already been released, including details of sightings by officials and police.
Nick Pope, who used to investigate the existence of UFOs for the MoD, said the files should contain some fascinating sightings.
However, referring to what is often called the most famous UFO claim in history – sparked by claims an alien spaceship crashed in New Mexico, US, in 1947 – Mr Pope added the soon-to-be-released files are probably not a "UK Roswell-style UFO in a hangar style cover up".
When the release of the files were stalled in 2014, which the MoD blamed on "additional processing requirements", Mr Pope sympathised with alien researchers.
He said at the time: "This massive delay will have conspiracy theorists up in arms. It looks like the MoD is stalling.
"The suspicion will be that there's a bombshell in these files and that the Ministry does not know how to handle it.
"I can understand why conspiracy theorists will be angry and suspicious."
Mr Pope worked at the MoD for 21 years, but was specifically assigned to investigate UFOs for a three-year period.
He told Express.co.uk today: "Coincidentally, to World UFO Day, the government just announced the date for the release of the final batch of Ministry of Defence UFO files.
"The fact that there is a World UFO Day shows the public's ongoing fascination with one of the great mysteries of our time. Having worked on the MoD's UFO project I'm sorry to say that we don't have any crashed spaceships hidden away in some RAF hangar, as some believe, but we do have some fascinating and unexplained cases in our files."
Today's World UFO Day is the fifteenth to be held on the anniversary of the Roswell mystery, when a UFO was alleged to have crashed near Roswell in New Mexico in July 1947, before being squirelled away by the military with aliens still inside the craft.
It is then claimed officials covered up the spacecraft's crash as being a downed weather balloon.
The 'Redlesham Forest incident', which is alleged to have taken place near RAF Woodbridge, Suffolk, in 1980, saw US Airman First Class John Burroughs, who was stationed there, exposed to radiation after a mystery "UFO visitation".
He has since won damages from the American military, but still wants answers about what happened and hopes they will be in the new files.
Pat Frascogna, his lawyer, said: "We know there is information contained in these MoD files about the Rendlesham Forest incident because the MoD clearly indicated so in responding to a Freedom of Information request by John Burroughs last year."
UFO hunters are keeping their eyes firmly on the skies today and tonight to celebrate the global fascination with the flying saucer.
According to the World UFO Day website, it is dedicated to "raising awareness about the undoubted existence of UFO’s and with that intelligent beings from outer space."
It is also part of a campaign to get international governments to "declassify" their so-called confidential "X-Files" on UFO sightings throughout their history.