A loophole in the Human Fertilisation and Embryology Bill could permit some reproductive cloning without the need for fresh primary legislation, the Government has admitted.

While the update to fertility law maintains the ban on creating cloned babies, it has inadvertently made it much simpler for ministers to overturn it. If a reproductive cloning technique could be shown to be suitable for preventing the birth of children suffering from a rare type of genetic disease, it could be cleared for clinical use without changing the statute book.

Ministers would simply have to issue new regulations that permit this application of cloning. These would then need to be approved by a simple vote of both Houses of Parliament, instead of the laborious primary legislation required at present.

Reproductive cloning involves placing the nucleus of an adult cell into an empty egg, and then implanting the cloned embryo into a woman's womb. Any resulting baby would be genetically identical to the DNA donor. The procedure is banned under the 2001 Reproductive Cloning Act which was introduced because of scientists' fears about safety and widespread ethical concerns. This law will be repealed by the HFE Bill, which contains fresh provisions that prohibit such cloning.

The Department of Health, however, has accepted that the legislation contains a flaw that could in theory make it easier for the ban to be lifted. Dawn Primarolo, the Health Minister, insisted in a debate during the Bill's committee stage that the Government has no intention of using this new power under any circumstances. She added that as new regulations would have to be approved by Parliament, there will still be democratic safeguards against cloning.

Opposition MPs, however, have expressed concern at the watering down of the cloning ban. Evan Harris, the Liberal Democrat science spokesman, said: “There is no prospect of this Parliament, or future Parliaments, passing regulations that would allow human reproductive cloning. But it would clearly be better, for the sake of consistency and reassurance, for the Bill to do what we all thought it would do, which is totally to ban human reproductive cloning in primary legislation.” He said it would be relatively simple for the Government to redraft the Bill to exclude all possibilities.

The problem has arisen because of clauses that regulate a new approach to preventing diseases caused by faulty mitochondria - cellular “batteries” that provide energy. The flaw in the legislation, first highlighted by a small pressure group called Human Genetics Alert, is that not all mitochondrial diseases are caused by defects in mitochondrial DNA. Some are caused by defects in the nucleus.

A spokesman for the Department of Health said: “This power can only be used to permit the practice of curing an embryo or an egg of a serious mitochondrial disease. The Government will not use this power to permit the practice of reproductive cloning.”

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