The attempt by US fertility expert Panos Zavos to clone a human has failed.
Dr Zavos was trying to create a cloned baby
The controversial scientist recently announced he had successfully implanted a cloned human embryo in a woman's womb.
But tests have shown that the woman did not become pregnant.
Other scientists have criticised Dr Zavos's work, but he has pledged to continue his attempts to successfully clone a human.
Dr Zavos told a sceptical news conference in London three weeks ago that he had implanted the embryo into a 35-year-old woman.
He said the embryo had been created using her immature egg and a skin cell from her husband.
Reproductive cloning takes DNA from the donor and transfers it into an egg which has had its nucleus, and therefore most of its own genetic material, removed.
It is similar to the technology used to create Dolly the sheep, but its use on humans is illegal in the UK.
Animal tests have shown cloning produces a high number of miscarriages, and deformities in pregnancies which result in a live birth.
Dr Zavos's team checked for a hormone which would indicate a pregnancy had developed two to three weeks after the embryo was implanted - but the results were negative.
The scientist has said that the materials and methods he used in his research will be published in a peer-reviewed scientific journal "in the near future".
Dr Zavos told the London press conference: "Successful or not, we are going to do another one and another one and another until we succeed."
Other scientists have said human cloning should be completely outlawed.
Lord Robert May, president of the Royal Society, said "cowboy cloners" caused great public anxiety and should be stopped.
Professor Richard Gardner, chairman of the Royal Society's working group on cloning, said: "We utterly condemn any attempt at present to clone human beings, which would be medically unsafe, scientifically unsound and ethically unacceptable.
"This appears to be yet another publicity stunt, lacking any evidence to verify the claims.
"If Dr Zavos wants his claims to be taken seriously, he must present to the scientific and medical community details of what he is doing, who he is working with, where the work is being carried out and who is funding it. Until then, we remain extremely sceptical."