The legality of the licences that allowed the creation of Britain's first human-animal hybrid embryos is to be challenged by a Christian group, The Times has learnt.

The Christian Legal Centre (CLC) has instigated a judicial review of the decision by the Human Fertilisation and Embryology Authority (HFEA) to approve two teams to start the controversial experiments, arguing that the watchdog acted beyond its powers.

In January, the authority awarded licences to scientists at King's College London and the University of Newcastle-upon-Tyne to create cytoplasmic hybrid or “cybrid” embryos by inserting human DNA into empty cow eggs.

Though these cybrids are 99.9 per cent human in genetic terms, they contain a very small quantity of animal material. The scientists want to use them to create stem cells with which to study diseases such as Alzheimer's and Parkinson's.

Last week, it emerged that the Newcastle group had already produced cybrids for the first time in Britain, though its work has yet to be peer-reviewed or published.

The House of Commons is also preparing to consider the issue next month, when it debates the Human Fertilisation and Embryology Bill, which contains clauses that would formalise the legal status of these embryos.

The CLC confirmed this evening that it was challenging the HFEA ruling, which it argues exceeded the regulator's legal authority.

Under the 1990 Human Fertilisation and Embryology Act, it is empowered to licence research using human embryos, and the watchdog's lawyers advised it that cybrids were covered by its remit.

The Christian group disagrees, and is also questioning the authority's decision that the experiments were “necessary or desirable” for medical research.

Andrea Minichiello Williams, director of the CLC, said: “We are submitting a judicial review on the basis that the HFEA did not have the authority to grant licences for the creation of animal-human hybrids under the 1990 Act, which clearly refers to human embryos. They are therefore acting ultra-vires.”

She added that the HFEA had “pre-empted the will of Parliament” by ruling on an issue that it knew was about to be debated by MPs.

The embryology authority confirmed that it had been informed of the CLC's intention to seek judicial review.

The HFEA’s right to approve the work was backed last year by the Commons Science and Technology Committee, which saw the authority’s legal advice.

Evan Harris, a Liberal Democrat member of the committee, said tonight: “It was clear from a combination of the 1990 Act and the cloning regulations passed in 2001 that this work was licensable. These embryos are human.

“Even if that interpretation is wrong, that would mean that these experiments are perfectly legal because they are not subject to any regulation at all. The one thing it is impossible to argue is that they are banned.”

James Lawford Davies, a solicitor at Clifford Chance who specialises in embryology law, confirmed that even if the challenge succeeded, the work would remain legal. “All it would do is to leave this area unregulated,” he said.

He added that the HFEA decision could be overturned only if a judge decided that its interpretation of the embryos as human was “irrational, unreasonable or unlawful”.

He said: “The fact that some people might disagree does not leave the HFEA vulnerable. It is also irrelevant that Parliament is discussing the issue. The HFEA is obliged to rule on licence applications as they are received, and had it refused to do so it would have been vulnerable to judicial review from Newcastle or King’s.”

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