We should not, as a society, grow life to destroy it

President Bush

ACT said the single, six-celled embryo it had created would help the firm to develop novel treatments for degenerative diseases - illnesses such as Parkinson's and diabetes. It was not intended to make babies, ACT said.

Mr Bush is opposed to all forms of cloning and recently supported moves in the House of Representatives to outlaw both reproductive and therapeutic cloning.

The Vatican and the European Commission have also condemned ACT's research project.

'Morally wrong'

Mr Bush has urged the US Senate to act on legislation passed by the House of Representatives earlier this year which would ban the sort of procedure used by ACT.

Stem cell research is proving controversial

"We shouldn't as a society grow life to destroy it," said President Bush.

"And that's exactly what's taking place. And I have made that position very clear, I haven't changed my mind. And this evidence today that they are trying to achieve that objective to grow an embryo in order to extract its stem cells in order for that embryo to die is bad public policy. Not only that, it's morally wrong in my opinion."

His view was echoed by a Vatican official. Monsignor Tarcisio Bertone told Italian television that therapeutic aims may be praiseworthy, but did not justify the production and destruction of human beings.

"Notwithstanding the humanistic intents... this calls for a calm but resolute appraisal which shows the moral gravity of this project and calls for unequivocal condemnation," the Vatican said in a statement.

"What we have before us are human embryos and not cells... life which must preserve its dignity like every other human life," it said.

'Unconvincing evidence'

The European Commission said it opposed the research and would not finance any similar projects.

"Not everything scientifically possible and technologically feasible is necessarily desirable or admissible," European Research Commissioner Philippe Busquin said in a statement.

Not everything scientifically possible and technologically feasible is necessarily desirable or admissible

European Research Commissioner Philippe Busquin

Michael West, Advanced Cell Technology Chief Executive countered: "Our interest is not to clone a human being; it's to clone human cells for the treatment of human disease."

ACT's decision to publish details of its work has drawn criticism from some scientists working in the fields of cloning and stem cells.

Ian Wilmut, one of the scientists that produced Dolly the sheep clone, doubted whether the evidence produced in the company's scientific paper amounted to proof that cloning had actually taken place.

And this was position was taken up by John Gearhart, of Johns Hopkins University, who was one of the first scientists to isolate and maintain human embryonic stem cells in the lab.

"They are promoting this very hard as a scientific advance based on very preliminary and unconvincing evidence. And I think that from that standpoint it should not have been published."

Newspaper editorials

Kevin Eggan, who has cloned mice at the Whitehead Institute in Cambridge, Massachusetts, said the short-lived embryos might indicate a problem with the cloning process when applied to humans.

"It may be a signal that the technique everyone has been using in other species may not work for humans."

It may be a signal that the technique everyone has been using in other species may not work for humans

Kevin Eggan, cloning researcher

Randall Prather, who works on pig cloning at the University of Missouri-Columbia, said he thought ACT's efforts were worthwhile. "It's a success from the respect that they completed the procedures," he said.

And Peter Mombaerts, a mice-cloning researcher at New York's Rockefeller University who is also a scientific adviser to ACT, said: "This will be regarded absolutely as a historical paper. It doesn't really show that much, but it's the first report of a cloned human organism."

The New York Times and The Washington Post stepped into the fray on Tuesday by publishing editorials on the issue.

Barring all research into therapeutic cloning can't be justified

Washington Post

"Barring all research into therapeutic cloning can't be justified," the Washington Post wrote, saying it was too early in the research process to judge it on its potential future merits.

The New York Times called the discovery a "modest advance along the road toward therapeutic cloning", suggesting the privately-held company may have hurt its own cause by creating a media frenzy around the announcement.

"Unfortunately, by rushing to print with such preliminary results... Advanced Cell Technology has invited legislative retaliation that could cripple the very research it is attempting to pioneer," the paper opined.