Italian fertility specialist Severino Antinori, who last year announced his intention to create the world's first human clone, has been quoted as saying one woman in his program was pregnant but he has since refused to confirm or deny it.
"Our project is at a very advanced stage. One woman among the thousands of infertile couples in the program is eight weeks pregnant," Gulf News, an English-language newspaper in the United Arab Emirates, on Wednesday quoted Antinori as saying.
It said Antinori, who did not give any further details, had been responding to a question at a lecture at the Zayed Center for Follow-up and Coordination, an Abu Dhabi think tank.
It was unclear if Antonori had clearly stated that the woman's pregnancy was a result of cloning.
Contacted by telephone on Saturday, Antinori told Reuters "I am not talking to journalists" before hanging up.
There was no information as to where the woman was, or from whom the alleged fetus was cloned, if it was.
Cloning and fertility experts expressed strong doubts over the report.
Dr Ehab Kelada, clinical director at the London Fertility Center, said Antinori must clarify the report immediately.
"The scientific community will be very alarmed," he said.
"If this report is true, it is shocking. We don't know how safe cloning is for humans and it is dangerous to embark on this path without proper regulations or guidelines."
Rudolf Jaenisch, professor of biology and a leading cloning scientist based at the Whitehead Institute at the Massachusetts Institute of Technology, said he was extremely angry at the news but very skeptical.
He said the scientific community would have no way or verifying whether the baby, if it existed, was a clone or a normal child.
"I do not trust these people to tell us the truth," he said.
"It is totally outrageous and irresponsible to attempt cloning of humans when we know there is a very high probability of severe abnormalities, even if the baby survived to birth, which is extremely doubtful. In fact, death before birth would be the best outcome."
Richard Nicholson, editor of the Bulletin of Medical Ethics in Britain, said he was skeptical about the report because of the technical difficulties which had to be overcome.
But he believed it was only a matter of time before a woman was implanted with a cloned embryo.
The idea of a human clone has met with outrage around the world, despite the promised benefits of some avenues of research.
Antinori's plans have been condemned by the scientists who produced the world's first successfully cloned mammal, Dolly the sheep after a series of failed attempts.
Harry Griffin, assistant director of Scotland's Roslin Institute, has said any attempt to clone a child would be wholly irresponsible.
Antinori's move prompted the United Nations to set up a panel last year aimed at drafting an international treaty to ban the cloning of human beings.
The treaty drafting process is expected to take years, but Antinori's reported announcement is likely to give more urgency to the debate, which began in February.
Human reproductive cloning is banned in Britain and some other countries. But in many nations it is unclear how existing laws cover this area of scientific development.
Antinori has been working with Panos Zavos, a former professor at the University of Kentucky in the United States, to clone fetuses for infertile couples.
He achieved fame a few years ago by helping a 62-year-old woman become pregnant with a donated egg.