"There is a very real possibility that a virus can jump from the animal to the human, with dire consequences. And if one's got an animal transplant, to ensure the person did not suffer the dangers of the virus, they would have to guarantee never to have children. "
She said she was worried that Lord Winston felt the need he had to go to the US to continue his research. "America is pretty much unregulated. If someone goes there, it usually means there is something upsetting the British authorities. They wouldn't refuse a licence for no good reason."
British regulations prevent Lord Winston from being able to conduct key elements of his research in the UK as the Department for Environment, Food and Rural Affairs will not release the post-mortem specimens from the pigs he has used in his research.
Lord Winston said: "I think that Ruth Deech showed a shocking misapprehension and I find it very worrying that somebody who has been a regulator could actually just simply say: ‘Well of course, the regulators know best.' I feel very disappointed about that."
According to halachic experts, there is no ethical or halachic problem in using pigs for human transplants.
Rabbi Chaim Rappaport, chief adviser to the Chief Rabbi on medical ethics, said: "Pigs are the closest thing [to human beings] that seem to have the potential to work. It would hopefully lessen the problems involved in donating human organs, and save lives. There is nothing wrong with having the body parts of a pig. If it works, it will be a blessing."
Rabbi Yehuda Pink, chair of the West Midlands Jewish medical ethics forum, said: "Genetically modifying pigs to produce organs for humans would be a tremendous step forward."
Baroness Deech said she did not have a problem with the use of pig organs from a kashrut perspective, but said her concern was to do with xenotransplantation - using organs from animals for humans - generally.