The professor's comments were made during an unreported debate last week on sex selection, which was held as part of the Commons Science and Technology Committee's consultation on human reproductive technologies.

Prof Harris, who is also a professor of bioethics at the University of Manchester, was asked what moral status he accorded an embryo and he endorsed infanticide in cases of a child carrying a genetic disorder that remained undetected during pregnancy.

He replied: "I don't think infanticide is always unjustifiable. I don't think it is plausible to think that there is any moral change that occurs during the journey down the birth canal."

He declined to say up to what age he believed infanticide should be permissable.

Prof Harris, who is one of the founders of the International Association of Bioethics and the author of 15 books on the ethics of genetics, was condemned for his remarks.

Julia Millington, the political director of the ProLife Party, who posed the original question to Prof Harris, called the admission "absolutely horrifying".

"Infanticide is murder and is against the law. It is frightening to think that university students are being educated by somebody who endorses the killing of newborn babies and equally worrying to discover that such a person is also a member of the ethics committee of the British Medical Association."

She continued: "Prof Harris is the Establishment's preferred bioethicist, a member of the Human Genetics Commission, and has acted as ethical consultant to the Department of Health and to numerous international bodies. In such a climate is it any wonder that a baby has been aborted in the UK at seven months for a cleft palate?"

Prof Harris said that he stood by his remarks, which he claimed had been elicited "in response to goading" from pro-life campaigners.

"People who think there is a difference between infanticide and late abortion have to ask the question: what has happened to the foetus in the time it takes to pass down the birth canal and into the world which changes its moral status? I don't think anything has happened in that time.

"It is well-known that where a serious abnormality is not picked up - when you get a very seriously handicapped or indeed a very premature newborn which suffers brain damage - that what effectively happens is that steps are taken not to sustain it on life-support.

"There is a very widespread and accepted practice of infanticide in most countries. We ought to be much more upfront about the ethics of all of this and ask ourselves the serious question: what do we really think is different between newborns and late foetuses?

"There is no obvious reason why one should think differently, from an ethical point of view, about a foetus when it's outside the womb rather than when it's inside the womb."

Prof Harris added that it was up to individual families to make a decision on the future of their child and that he was not concerned that such a course of action could lead to infanticide for cosmetic reasons.

"I don't believe there is any such thing as a slippery slope," he said. "I think that we are always on one. It is our responsibility not to avoid the moral choice.

"We shouldn't make a bad decision now because we fear it will lead us to make another bad decision in the future. We should make a good decision now and have the courage to believe we will make a good decision in the future too."

The Rev Joanna Jepson, the Church of England curate who is going to the High Court to try to block late abortions for "trivial reasons" such as a cleft palate, said: "It is frightening to hear anyone endorsing infanticide but it is shocking when the person is responsible for teaching others."

"This affirms the need for an investigation into the practice of abortion. We have already seen, in the cleft palate case, how the law needs to provide more rigorous protection for such babies but, with medical practitioners such as John Harris at work, there is no question of our fundamental need to reaffirm the human value of every baby's life, no matter what its sex or disability."

A spokeswoman for the British Medical Association said: "These views of Prof Harris are personal views and do not reflect the views of the committee or the BMA, which is utterly opposed to the idea of infanticide."

END