'Our intention is not to create cloned human beings, but to develop life-saving therapies'

The creation of an embryonic human clone that develops normally and lives for at least 14 days in the laboratory – the legal limit in the UK for "normal" test-tube babies – would rival some of the greatest scientific breakthroughs.

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First clone of a human embryo created

The creation of an embryonic human clone that develops normally and lives for at least 14 days in the laboratory – the legal limit in the UK for "normal" test-tube babies – would rival some of the greatest scientific breakthroughs.

It would mean that scientists could harvest the cloned embryo for the all-important embryonic stem cells that are seen increasingly as the vital elements in the fight against a host of intractable illnesses such as Parkinson's, heart disease and the many disorders of old age.

It would also mean that there would be no intrinsic barrier to creating a cloned human embryo that could be implanted into the womb of a woman who could then give birth to a baby that would not have been conceived by sexual reproduction – something that has not occurred in human history.

The announcement yesterday by Advanced Cell Technology (ACT), an American biotechnology company based in Worcester, Massachusetts, that it has created a cloned human embryo that has developed to the six-cell stage represents an important preliminary step in the direction of a fully viable cloned embryo – but it falls just short of achieving the goal itself.

ACT, which has a track record in animal cloning, is the first organisation to publish a peer-reviewed scientific paper detailing how its scientists were able to create a human-cloned embryo by transferring the nucleus of an adult cell into the unfertilised human egg that had its own nucleus removed.

However, because the embryo did not live beyond the six-cell stage, the company will have difficulty convincing sceptics that it has made the important breakthrough that its publicity machine was declaring it had achieved.

Other scientists claim to have achieved the same success but because their experiments were not published in a scientific journal they lacked credibility. Scientists from ACT, however, have published their research in the Journal of Regenerative Medicine. Michael West, chief executive officer of ACT, said the aim of the research was "not to create a cloned baby" but to produce embryonic stem cells that are capable of mending damaged tissues or organs in what is termed "therapeutic" cloning.

Reproductive cloning, when a cloned embryo is allowed to develop into a baby inside the womb, may not be the goal of ACT and the many other scientists at the forefront of cloning research but it is one possible use of the same technology.

In the UK, government ministers had been led to believe by their lawyers that the existing Human Fertilisation and Embryology Act in effect banned anyone attempting human reproductive cloning, but a High Court judge ruled otherwise earlier this month.

The Act's definition of an embryo – the final result of fertilisation, the fusion of sperm and egg – did not cover an embryo created by the transfer of an adult cell nucleus to an unfertilised egg with its own nucleus removed.

The Government is now set on rushing emergency legislation through the House of Lords to make it illegal for anyone to transfer an embryonic clone into a womb – but not it seems to cover the export of a cloned embryo to a country where this is not illegal.

Human cloning is controversial but not illegal in America. Unlike in Britain, there is no regulation of private-sector laboratories experimenting with embryos and little likelihood it will be banned in the near future. But federal law prevents only the funding of cloning research by the government – leaving the private sector a free hand to carry out research. There have been moves towards a complete ban, but those have been put on hold by the 11 September attacks, with legislators concentrating on anti-terrorism and economic stimulus packages.

American scientists are nervous about being seen to be involved in anything that smacks of cloning human babies. "Scientifically, biologically, the entities we are creating are not individuals. They're only cellular life," Dr West said yesterday.

This is not the view taken by the Catholic Church and other "pro-life" groups opposed to human embryo research. John Smeaton, national director of the Society for the Protection of Unborn Children said: "This appears to be a disturbing and deplorable development. It underlines the need for the Government's Bill to be fundamentally changed so all forms of human cloning are banned."

Other scientists were critical of ACT on the grounds that it is trumpeting something that is not yet the Holy Grail of human embryonic cloning. Professor Ian Wilmut, of the Roslin Institute near Edinburgh, who led the team that created Dolly the sheep, said the ACT research was still preliminary although he accepted that it went further than other studies by publication in a journal.

Professor Wilmut said scientists had claimed at least twice before to have created cloned embryos to the six or eight-cell stage. One claim was by Korean scientists in Seoul who said they destroyed the embryos and another was by Jose Cibelli, vice-president of ACT, who led the current study.

Professor Wilmut said: "Even if you took the nucleus out of an unfertilised egg it would still develop to the six-cell stage under the right conditions without necessarily adding the nucleus of an adult cell. The fact that it did not develop beyond six cells suggests it is fairly lightweight research."

Yesterday's announcement may have more to do with commercial pressure than scientific achievement, he said. "In terms of what this says for human cloning, it is pretty irrelevant. Frankly, the fact that the company is announcing this now suggests it needs the publicity for refinancing," he said.

Although scientists have cloned a variety of mammals using the Dolly technique – including mice, goats and cows – other species, such as dogs, cats and monkeys, have proved more difficult. Professor Wilmut said cloning human cells might also be difficult.

Dr Cibelli dismissed suggestions the company was engaged in a publicity stunt, saying the findings indicated there was no biological barrier to cloning human embryos using the Dolly technique, a method which, in effect, "reprogrammed" a mature, fully specialised skin cell so that it possessed all the developmental potential of a fertilised egg cell.