The 7-pound baby was born Thursday by Caesarean section and will be home in three days, said Brigitte Boisselier, a chemist and CEO of a company that did the experiment. She wouldn't say where the baby was born; she did say the birth was at 11:55 a.m. local time.
Even before her news conference, other scientists expressed doubt that her group could clone a human.
Boisselier said the baby, dubbed ``Eve'' by the scientists, is a clone of a 31-year-old American woman. The woman donated the DNA for the cloning process, had the resulting embryo implanted and then gestated the baby, Boisselier said. If confirmed, that would make the child an exact genetic duplicate of her mother.
Boisselier, who wouldn't reveal any names, said the mother had resorted to cloning because her husband was infertile.
``The baby is very healthy,'' she said. ``The parents are happy. I hope that you remember them when you talk about this baby - not like a monster, like some results of something that is disgusting.''
Boisselier did not immediately present DNA evidence showing a genetic match between mother and daughter, leaving her claim unsupported.
Michael Guillen, a former science editor at ABC-TV, told reporters at the news conference he was lining up ``independent world-class experts'' to perform DNA tests on the mother and baby. He said he was not being paid by Clonaid.
Boisselier said results would come within nine days.
``You can still go back to your office and treat me as a fraud,'' she said. ``You have one week to do that.''
Most scientists, already skeptical of Boisellier's ability to produce a human clone, will probably demand to know exactly how the DNA testing was done before they believe the announcement.
Boisselier said she expects four more babies - from North America, Europe and two from Asia - to be born in a few weeks. Two of the couples are using preserved cells taken from their own children before their deaths, and one is a lesbian couple, she said.
The couples were not asked to pay for the procedures but some had invested in Clonaid, she said.
Boisselier said 20 more attempts were planned for January.
Clonaid was founded in the Bahamas in 1997 by Claude Vorilhon, a former French journalist and leader of a group called the Raelians. Vorilhon and his followers claim aliens visiting him in the 1970s revealed they had created all life on Earth through genetic engineering.
Boisselier, who claims two chemistry degrees and previously was marketing director for a chemical company in France, identifies herself as a Raelian ``bishop'' and said Clonaid retains philosophical but not economic links to the Raelians. She is not a specialist in reproductive medicine.
She resigned last spring from Hamilton College in Clinton, New York while working as a visiting chemistry professor, when her cloning efforts became public and sparked controversy.
Cloning produces a new individual using only one person's DNA. The process is technically difficult but conceptually simple. Scientists remove the genetic material from an unfertilized egg, then introduce new DNA from a cell of the animal to be cloned. Under the proper conditions, the egg begins dividing into new cells according to the instructions in the introduced DNA.
Legislation or guidelines to ban human cloning are pending in dozens of nations, including the United States. Several countries, including Britain, Israel, Japan and Germany, already have banned it. There is no specific law against it in the United States, but the Food and Drug Administration contends it must approve any human experiments in this country.
Boisselier would not say where Clonaid has been carrying out its experiments. Bush administration officials had said they were aware of rumors of an announcement but had no plans to comment until after the details were known.
In Rome, fertility doctor Severino Antinori, who said weeks ago that a cloned baby boy would be born in January, dismissed Clonaid's claims and said the group has no scientific credibility.
So far scientists have succeeded in cloning sheep, mice, cows, pigs, goats and cats. Many scientists say cloning is too risky because of abnormalities seen in cloned animals.
Among the possible pitfalls are premature aging and other health problems. Dolly, the world's first cloned sheep, born in 1996, developed arthritis at a relatively early age, but it is unclear if it is related to the cloning, one of her creators said earlier this year.
Last year, scientists in Massachusetts produced cloned human embryos with the intention of using them as a source of stem cells, but the embryos never grew bigger than six cells.
Dr. Robert Lanza of Advanced Cell Technology, the Massachusetts company, said before Boisselier's announcement that Clonaid has ``no scientific credibility.'' But he and other experts do not dismiss the possibility of success.