London, Jul 18 (IANS): Two Britons living in New Zealand have built a pair of bionic legs that allow paraplegics - those with complete paralysis of the lower half of the body - to walk again.

Bionic parts are electronic ones which replace body parts.

The invention, resembling a film prop from the Hollywood sci-fi drama "Robocop", has been unveiled seven years after the pair first sketched the concept on the back of a beermat.

Richard Little and Robert Irving, who grew up together in Fort William and went on to study engineering, expect to be swamped with demand from around the world when the device goes into production later this year, the Telegraph reported.

Known as Rex, an acronym for Robotic Exoskeleton, the legs weigh 38 kg and are operated by a small electric motor powered from a lightweight battery.

Wheelchair users move across to the device in a sitting position, strap themselves in, and direct its movements through a joystick and control panel on the arm.

Rex's makers say it can stand, walk on the flat or up gentle slopes such as a ramp, turn around, and go up or down stairs.

Paraplegic Hayden Allen, who had been told by doctors he would never walk again after he injured his spinal cord in a motorcycle accident five years ago, was one of the first to try Rex.

He demonstrated its abilities by walking across the makers' Auckland workshop to New Zealand Prime Minister John Key during a reception to mark the launch this week.

"I'll never forget what it was like to see my feet walking under me the first time I used Rex," Allen said.

"People say to me 'look up when you're walking' but I just can't stop staring down at my feet moving," he added.

Richard Little migrated to New Zealand in 1992 and was followed two years later by his friend Robert Irving.

He said the catalyst to develop Rex came when Irving developed multiple sclerosis, a debilitating disease in which the body's immune system eats away at the protective sheath that covers the nerves.

"In addition, both of our mothers are in wheelchairs, so we are aware of some of the obstacles and access issues faced by many wheelchair users," he said.

The pair drew the concept on a beermat in a pub and finished their first prototype four years later, Little said.

The price tag for overseas buyers will be about 97,200 pounds.