The Ministry of Defence official who investigated a UFO sighting which was seen by police officers in North Devon says the incident is still totally unexplained.

The North Devon Journal revealed last week that newly-disclosed documents from the National Archives showed that UFO sightings in the early hours of March 31, 1993, led to military fears about national defence.

Nick Pope was the person in charge of the MoD's UFO desk at the time and he said the release of the previously secret documents was a "blast from the past".

He told the Journal: "What was apparent to me was that for every report we got there were 10 to 20 sightings unreported. I remember talking to one of the police officers and he said that listening to the radio chatter, that was all they were talking about.

"There wasn't any resolution of this sighting but the common theme of a large triangular UFO that has cropped up many times since then."

He said to this day he "honestly does not know" what was seen that night, but at the time he was sufficiently concerned to highlight the incident as a possible breach of British airspace by an unknown aircraft.

Mr Pope said he was fairly confident the Americans were not lying when they said they had not been flying any prototype aircraft that morning, but he could not rule out activity by other nations. "Maybe it was Russia," he added.

At the time there were numerous reports, many from reliable sources such as on-duty police officers and military personnel, about a strange triangular aircraft with three lights.

A sergeant and police constable who had been on duty near Lynton noticed two bright lights approaching from the north across the Bristol Channel.

They stopped their patrol car and watched as the lights drew nearer to them. They also noticed a smaller third light between the other two lights.

The sergeant got the impression the three lights were attached to one large object, which he could not make out. Both officers saw two vapour-like trails, although they were more like "beams of light".

The mystery appeared to have been solved when it was revealed that a Russian rocket had been re-entering the Earth's atmosphere at around that time. The MoD conceded the majority of the sightings did not tally with the timing of the rocket.

There was talk in Parliament and the press at the time of the US Government testing an experimental aircraft called Aurora in the UK.

But the archives just released contain a restricted MoD minute from April 21, 1993, which states: "In summary, there would seem to be considerable evidence that a UFO of unknown origin has been operating over the UK.

"Given recent speculation about Aurora by both media and MPs, I am not sure that this is something we should necessarily let lie, although equally there would seem to be little else we can do."

Another minute states that the UFO was of "considerable defence significance".

Mr Pope, who worked at the MoD for 21 years, said the March 31, 1993, sightings were unusual because of the large number of reliable witnesses, and the fact that only 5% of UFO sightings remain unexplained; most turn out to be weather balloons, meteors, or aircraft.

"What we were really talking about," he said. "Was unauthorised penetration of British air space."