The British government Tuesday gave the creator of Dolly the Sheep (search) a license to clone human embryos for medical research into the cause of motor neuron disease.

Ian Wilmut (search), who led the team that created Dolly at Scotland's Roslin Institute (search) in 1996, and motor neuron expert Christopher Shaw of the Institute of Psychiatry in London, plan to clone embryos to study how nerve cells go awry to cause the disease. The experiments do not involve creating cloned babies.

It is the second such license approved since Britain became the first country to legalize research cloning in 2001. The first was granted in August to a team that hopes to use cloning to create insulin-producing cells that could be transplanted into diabetics.

Dr. Brian Dickie, director of research at the London-based Motor Neuron Disease Association (search), said the latest decision by the Human Fertilization and Embryology Authority (search) means "we are a step closer to medical research that has the potential to revolutionize the future treatment of neuron disease," an incurable muscle-wasting condition that afflicts about 350,000 people and kills some 100,000 each year.

The study of the stem cells is expected to help in developing future treatments. The cells would not be used to correct the disease.

While the latest project would not use the stem cells to correct the disease, the study of the cells is expected to help scientists develop future treatments, according to the Human Fertilization and Embryology Authority, which regulates such research and approved the license.

Stem cells are the master cells of the body. They appear when embryos are just a few days old and go on to develop into every type of cell and tissue in the body. Scientists hope to be able to extract the stem cells from embryos when they are in their blank state and direct them to form any desired cell type to treat a variety of diseases, ranging from Parkinson's to diabetes.

Getting the cells from an embryo that is cloned from a sick patient could allow scientists to track how diseases develop and provide genetically matched cell transplants that do not cause the immune systems to reject the transplant.

Such work, called therapeutic cloning because it does not result in a baby, is opposed by abortion foes and other biological conservatives because researchers must destroy human embryos to harvest the cells.

Cloning opponents decried the license Tuesday, saying the technique is dangerous, undesirable and unnecessary.

"What a sad and extraordinary volte face (turnaround) for the pioneer of animal cloning," said the London-based Comment on Reproductive Ethics. "Wilmut has always been the loudest voice in recent years warning of the dangers of mammalian cloning. And we remember how in the years following the birth of Dolly the Sheep, he assured the world he would never go near human cloning."

Wilmut has repeatedly condemned the idea of human cloning to create babies, but not so-called therapeutic cloning.

The status of cloning varies widely across the world, and most countries have no laws or regulation in place. It is prohibited in Switzerland and Italy, while Belgium, Singapore and Japan have regulations allowing it for medical research.

Australia has a moratorium on the technique until lawmakers decide what to do. In the United States, federal government money cannot be used for cloning projects, but there are no restrictions on privately funded research.

The United Nations is deadlocked over the issue and is scheduled to take it up again later this month. The United States and Costa Rica are leading a bid to ban all forms of cloning, while Belgium is heading a faction that wants to allow it.

"We recognize that motor neuron disease is a serious congenital condition," said Angela McNab, chief of Britain's Human Fertilization and Embryology Authority. "Following careful review of the medical, scientific, legal and ethical aspects of this application, we felt it was appropriate to grant the Roslin Institute a one-year license for this research into the disease."

Wilmut and Shaw plan to clone cells from patients with the incurable muscle-wasting disease, derive blank-slate stem cells from the cloned embryo, make them develop into nerve cells, and compare their development to nerve cells derived from healthy embryos.

The technique, called cell nuclear replacement, is the same as that used to create Dolly.

The mechanism behind motor neuron disease is poorly understood because the nerves are inaccessible in the brain and central nervous system and cannot be removed from patients.

"This is potentially a big step forward for (motor neuron disease) research," Shaw said. "We have spent 20 years looking for genes that cause (motor neuron disease) and to date we have come up with just one gene. We believe that the use of cell nuclear replacement will greatly advance our understanding of why motor neurons degenerate in this disease, without having to hunt down the gene defect."

Genetics expert Peter Braude of King's College, London, who is not involved with the work, said that studying how nerves go wrong in motor neuron disease and how it can be cured is particularly difficult and that cloning is the only way to produce the cells necessary to answer such questions.