Defence chiefs remain "open-minded" about life on other planets after revealing they logged more than a dozen UFO sightings above Oxfordshire in eight years.

Government files yesterday highlighted the number of sightings in the county reported by the public to the Ministry of Defence (MoD) between 1998 and 2006.

There have been three sightings in Oxford during the period, including a bright white halo seen heading north west in 2001.

City sightings also included an oval object with green, red and blue flashing lights spotted in 2000 and a spinning oval with about 250 lights reported in 1998.

In total, 13 reports had been logged with the MoD and the biggest year for sightings was the millennium, when four separate reports were recorded.

The most recent incident was of a structure which glinted like metal, spotted above Banbury in June last year.

Elsewhere, in June 2001, an object four times the size of a star was spotted shining brightly as it moved north over Eynsham.

Two months later, a person in Chipping Norton reported several very bright purple, green and white objects in the sky.

While in February 1998, a witness reported a very large object like a firework rocket descending over the A34 near Abingdon.

But UFO expert Michael Soper, from Marston, in Oxford, a member of the Contact International UFO research group, believes there have been hundreds of sightings in the skies above the county over the same period.

He said: "People here do report things relatively readily and state very closely what they see and with no embellishment at all."

He added that a family from Faringdon had notified him of a particularly nasty alien abduction, while Uffington and the Rollright Stones were known as 'window areas' because so many UFOs are spotted there.

He said: "Oxford gets exciting reports of objects in the sky and there are several reports of abductions in Oxfordshire."

Frances Morrill, 51, of Eynsham, saw a large orange and pink sphere above Wytham Woods in the late 1970s which she believes was a UFO.

She said: "It has stayed with me today. I know other people who have said they saw things up there.

"I think it's all kept secret because no one wants to scare us to death. I always keep my eye on the sky and haven't seen anything else - and I don't want to."

The MoD is preparing to publish all UFO files dating back to 1967, including witness reports of apparent UFO sightings - many by civil pilots and military personnel.

A spokesman for the MoD said: "We do not have any expertise or role in respect of UFO matters - or to the question of the existence or otherwise of extra-terrestrial life forms - about which we remain totally open-minded."

The MoD examines reports to see if UK airspace may have been compromised by hostile or unauthorised military activity.

The MoD said "rational explanations" - such as aircraft lights-- could be found if resources were pointed in the right direction.