Washington

Concern is mounting among US biologists that unconfirmed reports of the birth of cloned babies could force through legislation that will outlaw any cloning of human embryos, even for research purposes.

Senator Sam Brownback (Republican, Kansas) is set to reintroduce legislation in the next few weeks that would enact such a ban. In the past, Brownback has been unable to garner the 60 Senate votes that are needed to pass his legislation, in the face of trenchant opposition from researchers.

On 27 December, however, Clonaid, a company controlled by the Raelian sect, a religious group that believes in extraterrestrials, told a disbelieving world that a cloned baby had been born at an undisclosed location. The claim — for which no evidence has yet been presented — is likely to be the first of several over the next few weeks from various doctors around the world.

Whether genuine or not, the claim may serve to build support for Brownback's legislation. Importantly, his proposal has the backing of new Senate Republican leader Bill Frist (Tennessee), a heart surgeon who normally supports biomedical research. Frist was elected on 23 December after Senator Trent Lott (Republican, Mississippi) was forced to resign.

Brownback's bill is also backed by President George Bush, and is similar to a measure that has already been passed by the House of Representatives. Besides making reproductive cloning illegal, it would also outlaw 'therapeutic cloning' of embryos to produce stem cells for research purposes. A rival measure, that would allow therapeutic cloning while banning the cloning of babies, has the support of scientific organizations but lacks the votes to be passed in either the House or the Senate, observers say.