"It's technically possible to sew a head onto someone's body, and it's technically possible to connect up all the arteries so that you've got blood flow to the head, and I think it's possible to protect the brain from too much damage while all this is happening," he said.
"I think the real problem is connecting the spinal cord up and in reality we can't do that yet."
Dr Hammond-Tooke said a lot of research was going into spinal cord injuries, " and I guess if one could solve the problem with spinal cord injuries then you could start thinking about this kind of transplant".
"But at the moment it's really just science fiction."
Dr Hammond-Tooke told Newstalk ZB a body transplant was probably a few decades away, and the doctor who had announced the operation was probably just a headline-grabber.
"First of all, all he's really saying is we're not far away from doing it, and I guess he just likes the publicity."
Dr Canavero said in February that he was two years away from being able to perform the operation, and that he had developed a technique that would allow the spinal cord to be reconnected, by making a clean cut with an "ultra-sharp" blade.