This is despite Defence Secretary Gavin Williamson claiming he has 'no plans' to open the secret department.
Britain's UFO desk, which probed notorious sighting such as Shropshire's 'Cosford Incident', closed in 2009.
But Nick Pope, who ran the former Ministry of Defence desk from 1991 to 1994, believes parts of the government could still be investigating the phenomena.
This is because, he says, UFOs are a real 'threat to Britain's skies' and should be taken seriously.
And he said sightings might not just be 'extra-terrestrial visits' - but 'drones, Russian aircraft and atmospheric phenomena'.
Mr Pope told the Express & Star: "There are no circumstances where the MoD, the Royal Air Force and indeed the government as a whole shouldn't be making every effort to identify anything unusual operating in our airspace.
"It doesn't matter if you're a sceptic or a believer and it doesn't matter if you think UFO sightings are generated by drones, Russian aircraft, exotic atmospheric plasma phenomena, or extraterrestrials.
"If there's something in our skies, there are clear defence, national security, and air safety implications."
The official stance from the government says something different. There is, they say, no need to have an official desk operating any more.
"There is certainly no plans to open up the UFO desk at the MoD," Mr Williamson told the Express & Star.
As recently as November, airline pilots reported seeing red lights whizzing into the sky over Ireland, which some linked to alien visitors.
Perhaps the most famous sighting in the West Midlands is the Cosford Incident, which happened in 1993.
On March 31 that year, an RAF patrol reported seeing a UFO over the base. They described the object moving ‘at great velocity and at an altitude of around 1,000 feet’.
The UFO consisted of two white lights and a faint red glow at the rear, with no engine noise being heard, the report said.
What made the incident more bizarre was that dozens of triangular-shaped UFOs were reported on the night, travelling at speed across Western Britain.
A UFO was also reported at RAF Shawbury, in Shrewsbury, not long after.
It may, Mr Pope says, have been investigated by a secret American research team – and he insists something similar might already exist in the UK.
“All the things the MoD would need are already funded, for example our military radar network and imagery analysis capabilities,” he said.
“It would be a cost-neutral proposal and the work could be done concurrently with existing intelligence analysis tasks.”
In December 2017, US-based journalists uncovered a secret Pentagon study which ran between 2007 and 2012.
It probed around 12,000 sightings dating back decades.
Staff based on the project avoided using the term ‘UFO’ in their work to stay below government radar.
Mr Pope adds: “The intriguing irony is that there might already be a new UFO project, unknown even to the Secretary of State for Defence.
“In the US, the Pentagon’s UFO project AATIP (Advanced Aerospace Threat Identification Program) was hidden by a combination of factors: they carefully avoided any mention of ‘UFOs’, while much of the work was contracted out to the private sector.
“The whole thing was described using language that implied they were studying future aviation threats from aircraft, missiles and drones.
“I strongly suspect MoD intelligence staff have done a similar thing and are looking at ‘unknowns’ in parallel with more conventional next-generation aerospace threats.
“As long as you use terms such as ‘unusual aircraft’, ‘unconventional helicopter’ and suchlike, you can probably spin this as not having a UFO project at all, especially if most of your work involves conventional foreign aerospace threats.
“Those involved might not even have briefed defence ministers about the existence of such a project, which would give them ‘plausible deniability’.”
The Cosford Incident was probed by the MoD at the time, under Mr Pope’s watch. He says: “I had a major UFO event on my hands.”
Mr Pope believes public scepticism about aliens is the reason why many UFO sightings are not taken seriously – and many people are quick to talk about drones appearing in the sky.
He says: “Perhaps we should review the double standards implicit here, and take all reports of unidentified objects in our skies seriously, whatever we think they are.”