London - Artificial sperm and eggs could be available within 10 years for fertility treatment, according to research into human embryonic stem cells carried out by British scientists, The Times reported on Monday.

The research by professors Behrouz Aflatoonian and Harry Moore, of the University of Sheffield in central England, showed it could be possible to produce primordial germ cells - the precursors of sperm and eggs - from embryonic stem cells.

Once these were obtained, the best method would be to transplant them directly into a man's testis or a woman's ovary, where the environmental and hormonal conditions were right to turn them into sperm or eggs, the report said.

Therapeutic cloning would be necessary to ensure that the germ cells carried the patient's genes.

"This is probably ten years away from the clinic, we have a lot of work to do, and we have to prove it's safe," Moore told The Times.

New form of cloning

Previous research in the United States and Japan had shown that it was possible to produce primordial germ cells from stem cells in mice, "and one team has even produced mouse embryos using artificial sperm generated in this way", the report said.

Anna Smajdor, a medical ethicist at Imperial College London, said the discovery "opens new and challenging possibilities. Single men could even produce a child using their own sperm (with an artificial egg), opening the way to a new form of cloning. Women's fertility would no longer need to be curtailed at the menopause."

The research by Moore and Aflatoonian was to be presented on Monday at the European Society of Human Reproduction and Embryology conference in Copenhagen.