Stem cell research provokes strong emotions
An American billionaire has suspended a $60m donation to a California university in protest at recent political restrictions on stem cell research and cloning.
Jim Clark, the founder of internet companies such as Netscape and WebMD, said restrictions imposed on the research threatened to throw the United States into what he called the dark age of medical research.
Mr Clark is one of the most influential people so far to join the debate.
In the last few months, the House of Representatives has agreed that the human cloning - in all its forms - should be banned, and President George W Bush has announced limitations on the funding of embryonic stem cell research.
The two measures have provoked considerable debate and the fall-out is clearly far from over.
Future of medicine
Anti-abortion activists want to stop stem cell research altogether, because it involves the creation of human embryos which are destroyed once important cells have been removed.
Some scientists would also like to use cloning technology in the process - something that, in itself, is highly controversial.
But Mr Clark, a legend in Silicon Valley for his ability to spot trends in emerging technology, maintains that research using stem cells is vital to the future of medicine.
Writing in The New York Times newspaper, he said it seemed that creating genetically compatible skin cells for burn victims, pancreas cells for diabetics, nerve cells for people with spinal cord injuries and other potential advantages would soon be illegal in the US.
He accused the country's political leaders of ignorance and fear of the unknown.
Mr Clark, who once taught at Stanford University, also announced that he had suspended the second part of a $150m grant to set up a bio-medical centre there because Congress and the president were thwarting part of that research by supporting such restrictions.
The centre is already under construction and the president of Stanford University, John Hennessey, supported Mr Clark, saying that many scientists were concerned about the long-term impact of restrictions on human embryonic stem cell research.