Scientists in Britain have been given the first licence to clone human embryos, but only for medical research.

The move comes more than three years after Britain became the first country to authorize cloning to produce stem cells for medical research.

Britain's Human Fertilisation and Embryology Authority said it approached the issue cautiously.

"After careful consideration of all the scientific, ethical, legal and medical aspects of the project, the HFEA Licence Committee agreed to grant an initial one year research licence," said Chair Suzi Leather.

The researchers at Newcastle University, in the north of England, will now be able to create embryos as a source of stem cells to cure diseases, according to a university spokeswoman.

"It has taken a year of work," said Dr. Miodrag Stojkovic, saying she was pleased that regulators had "recognized the potential of this technology in modern medicine."

The researchers hope eventually to create insulin-producing cells that could be transplanted into diabetic patients.

Stem cells are the building blocks from which all organs are formed. Many scientists believe they hold vast promise for treating an array of diseases from diabetes to Parkinson's.

The stem cells are extracted when the embryo is still microscopic. Regulations dictate that the embryo must not develop beyond 14 days -- and never be allowed to develop beyond a cluster of cells the size of a pinhead.

Cloning work in the United Kingdom can only be done by scientists who've been granted special licences.

Canada's Parliament passed legislation this past spring banning cloning -- and limiting the use of embryos in research.

South Korea allows therapeutic human cloning, and France's parliament has given final approval to a law that approves stem cell research on human embryos, but only for a limited test period.

Both the United States and Japan prohibit any kind of embryo cloning.

Some religious and politically conservative groups consider stem cell research, especially cloning, immoral, because fertilized embryos must be destroyed to harvest the stem cells.