An Italian neurosurgeon has moved closer to his goal of transplanting a human head, revealing a virtual reality system that will "prepare patients for life in a new body".

Professor Sergio Canavero wants to carry out the operation for the first time next year, saying it could help those paralysed from the neck down to walk again.

Valery Spiridonov, a Russian man with a genetic muscle-wasting disease, has volunteered to be the first patient.

But putting someone's head onto someone else's body could lead to "unexpected psychological reactions" so US firm Inventum Bioengineering Technologies has created a virtual reality world that it says will help train patients such as Mr Spiridonov.

Inventum chief executive Alexander Pavlovcik said the virtual reality system would be used before the surgery to prevent these unexpected reactions.

He added: "We are combining the latest advancements in virtual reality to develop the world's first protocol for preparing the patient for bodily freedom after the transplantation procedure."

When Professor Canavero revealed the system during a conference at the Royal College of Physicians and Surgeons of Glasgow on Friday, he described it as "prepar(ing) the patient in the best possible way for a new world that he will be facing with his new body - a world in which he will be able to walk again".

Mr Spiridonov said it was "extremely important" in helping patients "get involved into action and (to) learn fast and efficiently".

Professor Canavero also displayed the knife that will be used for the head transplant - a custom-made blade that can control cuts to a micrometre (one millionth of a metre) to allow the precision required to cut the spinal cord.

He said that the knife, developed by an American professor, will allow a "clear cut of the spinal cord with a minimal impact on the nerves".

He told Sky News that he was looking to take the procedure global, saying that "Asia is moving, so expect more news coming out over the next few months" and "the UK is very well poised to do this".

He showed little concern for the views of his critics, some of whom have described his work as Frankenstein surgery.

He said: "To all the critics I say go and see what happens when you're affected by a wasting disorder...trade places with (Mr Spiridonov) and then you tell me.

"That's my counter criticism for the critics."

In January, Mr Canavero worked with Chinese researchers to do a head transplant on a monkey, connecting the animal's blood supply after the operation to prove it could survive without brain injuries.

The monkey was only kept alive for 20 hours, as the team did not join its spinal cords, meaning it would have been paralysed.