A secret US spy plane – the existence of which has never been officially admitted – may have been behind a number of UFO sightings over Shropshire, newly released files suggest today.

More than 70 witnesses, including police and military personnel, reported sightings across the country in locations such as RAF Cosford and RAF Shawbury, as well as locations over Devon, Cornwall and South Wales on March 31, 1993.

Many reports described a large, low-flying object, which made a low humming sound.

The sightings included several from RAF Cosford, near Telford, where police reported seeing two bright lights “flying at great velocity” above the airfield.

There was no engine noise and the lights made a slight red glow from the rear as they disappeared over the horizon.

According to a Met officer at RAF Shawbury, the lights were travelling “erratically at hundreds of miles per hour unlike any aircraft” and “appeared to be searching for something”.

The officer said he had never seen anything like it.

The head of the Ministry of Defence’s UFO desk wrote, in a briefing note to Sir Anthony Bagnall, assistant chief of the air staff, there was evidence of an unidentified craft evading UK defences.

He wrote: “You may wish to be aware of a recent particularly unusual incidence of UFO sightings over the UK, involving descriptions that match some of the reported characterisations of the so-called ‘Aurora’.”

The Aurora was the name given to an unmanned US reconnaissance aircraft supposedly developed in secret “black” programmes in the 1980s and alleged to be capable of hypersonic flight. Another suggestion was that it was Russian rocket.

A report said: “A representative of the British UFO Research Association said the sightings coincided with the decay of a Russian rocket which had been used to launch a satellite.”

In his message, dated April 22, the head of the UFO desk wrote: “Some of the reports state the object was moving at a very high speed, while some say it was hovering or moving very slowly.

“My staff have spoken to a number of the military and police witnesses, many of whom commented the object was unlike anything they had ever seen before.”

Sir Anthony replied: “In spite of the quantity of the many witnesses who reported the unusual sightings on March 31, I can add nothing to the debate.”

By Andrew Morris