The stem cells produced from cloned embryos will be used to produce material which may cure some of diseases, such as cancer, Parkinson's or Alzheimer's disease.

The Center for Life at Newcastle University said it was ready to start work straight away, but that it could be five years before patients would be receiving therapy. These stem cells will be taken from embryos in the first stages of development and will have the potential to become different kinds of tissue, according to therapeutic need.

"Therapeutic cloning will in the immediate future be a vital tool in harnessing the power of stem cells to treat some of the major diseases which threaten humankind," John Harris, professor of bioethics at the University of Manchester, told news agency AP after the license was announced. "This decision is a signal of our society's compassion and concern for those threatened by disease."

The go-ahead came when the British government's Human Fertilization and Embryology Authority approved the university's application -- the first approval since human cloning for medical purposes was made legal in Britain in 2002.

Britain thus joins South Korea on the cutting edge of research in the field. In February, South Korean scientists announced that they had cloned an embryo and extracted stem cells from it.

Critics hit out

But opponents of cloning have been quick to criticize the decision. A spokesperson for the organization Comment on Reproductive Ethics said that no human life should be sacrificed for the benefit of another, and that a human embryo, however produced, had as much right to life as anyone else.

In Germany, too, the initial reaction has been negative. The representative of the conservative Christian Democrats in the parliamentary commission on bio-ethics, Thomas Rachel, said the British Authority's approval would be illegal in Germany and several other European countries. He called on the German government to push for a Europe-wide regulation.

The United Nations is due to discuss later this year a proposal for an international treaty to ban both therapeutic cloning, such as the procedure which has just been authorized, and reproductive cloning, in which cloning is used to produce human beings.

Britain and other countries are lobbying for countries to be allowed to decide for themselves whether to permit therapeutic cloning.