Relying on a technique similar to the one used to clone Dolly the sheep, the approach would, in effect, produce a baby with two genetic mothers, the Washington Post reported yesterday.

A baby that might result from such a high-tech union would raise questions of which woman is the mother, or both.

Some medical ethicists described the research as ``profoundly disturbing,'' but typical of the fast-paced and loosely regulated field of reproductive medicine. It is not human cloning, scientists said, although it borrows cloning technology to produce the embryo.

The method empties the gene-packed nucleus from an egg donated by a fertile woman. Scientists then transfer the genes from the egg of an infertile woman into the hollowed egg to make a single recombinant egg. It is fertilised with spermprovided by a father and the resulting embryo is transplanted into the infertile woman's womb.

The method used by Dr Jamie Grifo of New York University was not tested on animals prior to being tried in a pair of infertile women. The university has approved the use of the method on as many as five women.

In remarks reported by the Post, Grifo said he recognised the ethical implications of the experiment. He said his team does not have sources of private funding and a ban on federal funding of embryo research, a consequence of the nation's ongoing abortion debate, made animal experiments impossible. ``It's not like we did this thoughtlessly,'' Grifo said.

Critics weren't willing to take Grifo at his word. ``Nobody knew exactly what he was doing,'' said Glenn Mcgee, a bioethics professor at the University of Pennsylvania. ``Transferring genetic material from one person's egg to another -- this never happens in nature.''

Others offered a more cautious assessment. ``It doesn't sound like genetic tampering.It sounds more like it's transferring the genes into a new environment,'' said Donna Lieberman of the New York Civil Liberties Union's reproduction rights project.

A new drug must pass several clinical trials before winning federal approval, and the process can take years to complete. But fertility research has far fewer barriers, and is propelled by the ambitions of curious scientists and the desperation of infertile couples.

So far, the procedure brought uncertain results. It failed in the first patient, who is 47, the second patient, age 44, is not scheduled for a pregnancy test until next week. Their names were withheld for privacy reasons.

The technique follows the Dolly method of inserting the DNA into a single-cell egg for implantation. However, Dolly was created from the genetic material of an adult body cell provided by its mother, rather than combining genetic material from two different eggs.

The method is close enough to human cloning that even Grifo concedes probably would be illegal toperform in California and other states with broadly written cloning laws.

Grifo described the process on Thursday at the annual meeting of the American Society for Reproductive Medicine in San Francisco.