Efforts to draw up a global treaty to ban human cloning have collapsed after countries failed to agree on whether such a ban should exempt 'therapeutic cloning' – the creation of cloned embryos to obtain stem cells for research.

At talks at the United Nations in New York last week, a group of about 40 nations, led by Costa Rica and the United States, pushed for a total ban covering both reproductive cloning – the cloning of a human to produce another human – and therapeutic cloning.

But a rival group of 14 countries, including the United Kingdom, Brazil, China and South Africa, proposed that the top priority should be a ban on reproductive cloning alone. They argued that that, given the diversity of views on the morality of therapeutic cloning – a technique that could help develop treatments for a range of degenerative diseases – individual governments should be left to decide whether or not to permit therapeutic cloning.

It is the second time that UN debate has reached a deadlock over therapeutic cloning. Last November, UN talks on the treaty – which was originally proposed by France and Germany in 2001 – were put on hold because of a failure to agree on precisely that issue (see Global human cloning ban put on ice).

Last month more than 60 science academies from around the world called on the United Nations to adopt a ban on human reproductive cloning, but urged against outlawing therapeutic cloning, arguing that it had "considerable potential from a scientific perspective" (see Science bodies urge support for 'therapeutic cloning').