The skies above Britain are visited by at least one UFO a month, the head of UK Air Traffic Control has admitted.
Speaking on BBC Radio 4's Today programme, Richard Deakin confirmed unidentified flying objects were being seen by his staff.
Mr Deakin said: "Occasionally there are objects identified that do not conform to normal traffic patterns. It does not occupy a huge amount of my time.
“There are approximately one a month."
The figures are backed up by Nick Pope, a former UFO investigator for the Ministry of Defence.
Also speaking on the programme, he revealed between 200-300 sightings a year were reported during his tenure.
“Most of the reports turned out to be misidentification of aircraft lights, weather balloons, meteors and satellites,” he explained.
He added: “It did leave us with one or two a month we found genuinely interesting. Of course, our mindset is it’s probably more likely to be Russian than Martian.”
Pope, who continues to work as a UFO investigator, said the most interesting sightings were those which came from police officers, pilots or military personnel.
He added: “There was no definitive smoking gun that these things were alien…however we never say never.”
While the MoD axed its UFO investigation bureau officially in 2009, Pope explained: “Unofficially people get around that by saying ‘unusual aircraft or ‘unconventional helicopter’.”
The Telegraph quotes a 2008 document from a UFO Desk Officer:“I thought it would be helpful if I gave you some details about the role of the UFO desk beyond the daily mechanics of the job, which are really quite simple.
“However, since the universe is a very large place and mankind has only explored a very small corner of it, we cannot rule out the existence of intelligent life on other planets.
“We therefore remain open minded on the topic. In the absence of proof either way, this position seems a perfectly sensible one.”
The plug was pulled on the £44,000-a-year post at the same time as the MoD’s dedicated UFO hotline number.
An MoD spokesman said: “In over fifty years no UFO report revealed any evidence of a potential threat to the United Kingdom.
“The MoD had no specific capability for identifying the nature of such sightings and there would be no benefit in such an investigation. Furthermore, responding to reported UFO sightings diverted MOD resources from tasks that were more relevant to defence.”
But the National Archives files also contain details of several 'sightings'.
Some of the documents relate to a series of aliens seen above West Wales in 1977. One hotel owner said a dome-shaped object landed "like the moon falling down" behind his hotel, from which two "silver suited 'faceless humanoids' emerged and began 'making measurements'".
Another saw a craze for releasing Chinese sky lanterns lead to a spate of reports flooding into the MoD of "golden orbs" seen in the sky.
One woman called the MoD "panicking [and] saying we had to ring her back (She left three messages saying this). She was petrified and so were her friends. She had never seen anything like this before."
Another man from County Durham was more sanguine.
He "saw similar lights but did not think they were UFOs as he didn't believe aliens would want to visit Houghton" reported the MoD.