Witnesses have described watching a green-tinged meteor flash across the evening sky.

The "fireball" shot over England and Wales in a northerly direction at around 9.45pm on Wednesday.

Experts believe the meteor might have formed from debris from Halley's Comet.

Many observers took to Twitter to report the phenomenon with sightings apparently recorded in Cornwall, Hampshire, Lancashire, South Wales and Worcestershire.

Reports suggested the meteor crossed Britain from the South East towards the North West.

Space scientist Maggie Aderin-Pocock said the meteor's size was unusual. She told the BBC: "It seems that this one was particularly large and particularly bright, which is why it's caught so much attention."

"It's quite likely to be part of the Eta Aquarids, which is the debris left by Halley's Comet. And twice a year we pass through the debris left behind by the comet and when this happens we see more of these shooting stars, but there must have been a large lump left behind which is what caused such a bright meteor to be seen."

Dr Aderin-Pocock said the shooting star, though unusually large, was likely to have been no bigger than a closed fist and would have travelled at speeds of around 150,000mph. "When something like that hits the atmosphere, it burns up really brightly," she said.

She said the green or blue flame emitted suggested there was copper in the meteor. The fireball would have been one of a number of shooting stars that crossed the sky as the Earth passed through a trail of dust left by Halley's Comet - an event which occurs twice each year.

Star-gazers can expect to see further meteors - around 10 an hour - streaking through the sky until May 20, Dr Aderin-Pocock said.