Josephine Quintavalle, of the pro-life group Comment on Reproductive Ethics, said it was "risky, dangerous" and a step towards "designer babies".

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But Josephine Quintavalle, director of Comment on Reproductive Ethics (Core), which opposes embryonic stem cell therapies, dismissed the research as "highly speculative".

BBC: Green light for US stem cell work

However, Mrs Quintavalle is queasy about research she views as meddling with human life, and fears it could create more problems than it solves.

BBC: NEWS | Health | 'Our aim is to help children'

Mrs Quintavalle said embryo research in the US using DNA from one man and two women was discontinued because of the "huge abnormalities" in some cases.

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When people look at an unborn baby sucking its thumb, they see it as a human being, says Josephine Quintavalle, of Alive and Kicking, a pro-life campaign group.

ECONOMIST: Abortion

"There are currently 58 diseases that are being treated using adult stem cells so the issue of stems cells has a positive side, providing the cells are obtained ethically, " Quintavalle told CNN.

CNN: Cloning success hailed, feared

But Josephine Quintavalle, founder of the public interest group Comment on Reproductive Ethics (CORE) described the use of human embryos for therapeutic treatment as "quite horrifying, " and said that stem cell research should focus on the use of adult stem cells.

CNN: Cloning success hailed, feared