We have no intention to step over dead bodies or deformed babies to accomplish this [cloning]

Prof Panos Zavos

Several members of a House panel indicated their desire for stricter controls after sitting through a congressional hearing in Washington on Wednesday, attended by a pro-cloning US fertility specialist and the leader of a group that wants to clone a couple's dead child.

Both the doctor and the group said they would forge ahead with their controversial plans to produce "carbon copy" children.

Panos Zavos, professor of reproductive physiology at the University of Kentucky, has already announced that he intends to try to clone humans within the next 12 months.

Stronger powers

"We have no intention to step over dead bodies or deformed babies to accomplish this," Professor Zavos told the investigations subcommittee of the House Energy and Commerce Committee.

Dr Brigitte Boisselier: Advising Clonaid

Professor Zavos said his team would be able to test embryos for defects before implanting them in a woman's womb. However, other researchers said this was impossible.

An official from the US regulatory authority, the Food and Drug Administration, said the agency currently could deny permission for human cloning experiments only on safety grounds.

Violators could face fines of up to $100,000 (£69,390) and a year in prison. Lawmakers said they supported giving the government stronger powers.

Dr Brigitte Boisselier, director of Clonaid, a cloning programme backed by a religious sect, also testified before the subcommittee.

Clonaid is an arm of the Raelian Movement, a group that claims to be the world's largest UFO-related organisation. Clonaid wants to clone a couple's dead child at a secret US lab.

Underdeveloped technology

Efforts to clone human beings are facing mounting criticism, from religious groups, scientists and politicians.

Panos Zavos: Claims to be able to screen faulty embryo clones

Scientists say cloning techniques are still too underdeveloped to attempt on humans. Experience with animals has shown that most clone pregnancies fail, or result in offspring being delivered stillborn or deformed.

In a letter to the journal Science, Ian Wilmut, one of the scientists who produced Dolly the Sheep, the first adult mammalian clone, and US colleague Rudolf Jaenisch, said attempts to clone human beings at the current time were "dangerous and irresponsible".

However, despite these concerns, few laws exist to stop anyone wanting to clone a human from doing so.

Only four US states, and 12 nations worldwide, have banned human cloning.