Just 135 sightings were reported by police and the Ministry of Defense in 2007 and only 97 in 2006, reported The Daily Telegraph Saturday, which obtained the figures under a Freedom of Information Act request.

"Something really bizarre is happening in the skies over the U.K.," said Malcolm Robinson, founder of the research group Strange Phenomena Investigations. "I've been dealing in sightings for 30 years and we currently have something very real which mankind cannot explain."

But British officials were more non-committal, although a spokesman for the Department of Defense insisted they remained open minded. He said as long as sightings presented no threat to British airspace, they were not investigated further.