A police helicopter went on a dramatic high-speed chase - in pursuit of some little green men.

The tale of the unexpected began when a suspected UFO was spotted next to the Sussex Police vehicle as it flew 1,000ft above Brighton.

Inside, crew members Sergeant John Tickner and paramedic Sean Mitchell sat mesmerised as the glowing object floated next to them before disappearing into the distance. They were so stunned they decided to follow it and used a thermal imaging camera to video events as they chased the mystery object for three minutes before giving up and returning to base.

Now their video is being pored over by UFO enthusiasts around the world in the belief it could provide evidence of life on other planets.

Experts say they are baffled by the Brighton phenomenon. But both Mr Tickner and Mr Mitchell are convinced they did not witness a close encounter of the third kind.

Mr Tickner, 50, who retired last week after 30 years with Sussex Police, said: "We were flying back from Beachy Head and at 1,000ft we didn't expect anything to join us. Not for a moment did we believe it to be anything sinister.

"We thought it was funny though so we chased it around for three minutes and were laughing and joking about little green men. None of us took it seriously."

The bizarre incident happened on the evening of August 11, 2000.

The crew passed the film footage to a TV company making a documentary about their work.

The story was picked up by a magazine and the film has been screened at a UFO conference.