Cloning of human embryos can go ahead in British laboratories - but those produced should never be brought to term, experts advising the Government said yesterday.
"Therapeutic" cloning, aimed at producing human tissues or treatments for victims of serious accidents or disease, would be permissible under the terms of the 1990 Human Fertilisation and Embryology Act, which licenses research on human embryos up to 14 days old.
But Ruth Deech, who chairs the Human Fertilisation and Embryology Authority, which polices the Act, said yesterday that it was important to distinguish "therapeutic" cloning from "reproductive" cloning, in which the sole aim would be to produce children which were copies of existing people.
The announcement, which opens the door a crack towards some sorts of human cloning, came as the Human Genetics Advisory Commission (HGAC) and the HFEA published a consultation paper on the subject of cloning, for which they are seeking public views before making fuller recommendations.
It is only a year since scientists at the Roslin Institute near Edinburgh announced that they had cloned a sheep, Dolly, from the udder cells of an adult ewe by removing the nucleus from a sheep's egg cell and replacing it with the nucleus from a cell from Dolly's "forebear". She was the first mammal cloned directly from an adult.
However, the subject poses problems for those trying to understand its potential, and limits, in order to regulate it. For a decade, cloning was a backwater in scientific research, after disappointing results in the 1980s when leading scientists declared that cloning from adult animals was impossible. Hence it was not laboratory mice or rats - the normal fare of mainstream research scientists - that were cloned first, but an unwieldy, commercial animal, the sheep.
Since then scientists and ethicists have gone into a frenzy over cloning, but the lack of research over the past decade means they have had little hard data on which to base their predictions about its uses and dangers.
"I think that it is a good step that the UK is doing this and having a public debate," Sandra Thomas, director of the independent Nuffield Council for Bioethics, said of the publication of the document. "It hasn't been done elsewhere - people have simply called for total bans."
Mrs Deech emphasised that so far nobody had asked for a licence to carry out human embryo cloning, but said the HFEA would not rule out future applications which met certain strict criteria. "It's possible that we will consider these applications on a one-by-one basis," she said.
But the authority and the commission agreed that implanting a cloned embryo into a woman's womb and allowing it to develop into a foetus should remain taboo. "That's the barrier," Mrs Deech said. "We will not go anywhere near cloning a whole human being."
The Act expressly forbids a similar technique to that which created Dolly, involving the replacement of an embryo cell nucleus to create a clone. But when it was drawn up, the lack of scientific interest in cloning meant no one envisaged clones being produced by nuclear transfer to an egg. So there is nothing explicitly in the law to prevent that process being carried out with human cells.
Sir Colin Campbell, chairman of the HGAC, said that it was important to dispel the "fantasies and fears" surrounding cloning. "I think what we probably want is to stop the wild and irresponsible notion of cloning whole human beings.
"But we would like the scientific analogues, the procedures that might in five years' time lead to curing of diseases, to continue."
The consultation group will be seeking responses to key technical and ethical questions about cloning over the next three months.
Its document is being posted on the Internet so it can be read by as many people as possible, at www.dti.gov.uk/hgac.