A maverick Kentucky scientist Saturday said he successfully made a cloned human embryo and transferred it to the womb of a 35-year-old woman.

The scientist, Panos Zavos, who operates several businesses that deal with fertility products and has frequently sought publicity for his interest in human cloning, refused to say who the woman is or where the procedure was performed. Nor did he offer evidence of having made such an embryo, raising immediate suspicions that his announcement is but the latest in a series of cloning-related hoaxes in recent years.

Last year, a group of cloning advocates from an obscure religious group said it had produced a cloned baby, but never offered any evidence.

Zavos made his announcement at a news conference at a hotel in England. In a telephone interview afterward, he said he had retrieved three immature eggs from the ovaries of the woman, who he said had experienced premature menopause.

He said he grew one of those eggs to maturity in the laboratory, removed its DNA and then added DNA from a skin cell taken from her husband — a procedure that, in theory, could lead to the creation of an embryo and baby genetically identical to the father.

Zavos said the procedure was done two weeks ago — too recent to know whether the embryo has implanted in the uterine lining to create a pregnancy.

“When we confirm this with a pregnancy test, we’ll bring you up to date,” he said. “But the embryo was developing very well. It’s remarkable.”

Although a few other scientists have said they made cloned human embryos, none has reported getting the embryos to produce more than a few cells before dying.

Marian Damewood, president of the American Society for Reproductive Medicine, which represents fertility doctors, joined others in casting doubts. She said the organization would “deem any attempt to transfer a cloned human embryo into a woman for gestation and birth unethical.”