Infertile couples will be asked to hand over spare embryos for research purposes, under proposals to be announced by the Government today.

Infertile couples will be asked to hand over spare embryos for research purposes, under proposals to be announced by the Government today.

Women receiving in-vitro fertilisation (IVF) treatments will be presented with consent forms to allow scientists to retain extra embryos not needed for fertility reasons. The move, which was last night attacked by pro-life campaigners, is guaranteed to present IVF couples with an unprecedented moral dilemma.

The Government is proposing to extend the law on the use of human embryos to include research into "stem cells", which can be used to treat a variety of disorders, from heart disease to Parkinson's. It will also ask women to donate unfertilised eggs for research into "therapeutic cloning", when cloned embryos are created to generate stem cells that will not be rejected when transplanted.

Liam Donaldson, the Chief Medical Officer for England, is expected today to recommend that limited permission for "therapeutic cloning" should be granted on medical grounds.

His announcement will be welcomed by many scientists who claim cloning research will allow major progress in combatting currently incurable diseases. Researchers want to remove stem cells from embryos less than 14 days old and grow them to provide replacement tissue. Many scientists claim that the most feasible source of embryonic stem cells will be infertile women undergoing IVF, a treatment that produces multiple embryos.

The Department of Health will recognise this in its recommendations today, when it will make clear that IVF patients will be offered the chance to sign a consent form for stem-cell research. Sources within the department say that no pressure will be put on any patient to sign and that they will be given impartial advice.

To calm fears of "Frankenstein" cloning, Professor Donaldson will make it clear that the new rules would not allow human embryo clones to be transplanted into a woman's womb. In recognition that the whole area of cloning is a matter of individual conscience, MPs will be given a free vote on the recommendations.

Religious groups and anti-abortion campaigners have vowed to oppose the measure, but leading scientists have claimed that the UK should be allowed to join other countries in the research.

Ultimately, the idea's backers claim that embryos cloned from one or more of a patient's cells could solve the serious problem of transplant tissue being rejected. Some have even suggested that entire replacement organs could be grown in the laboratory in future.

Last night Jack Scarisbrick, national chairman of the charity Life, which opposes such research, said that most infertile couples were determined to produce viable embryos and would be horrified by the request to use their "spares".

"We will be bombarded with the argument that these embryos are going to be thrown away anyway and you might as well use them. But this is a question of the dignity of human life," he said. "The human embryo deserves the full respect of a human being. Thoughtful people will campaign against allowing their offspring to be used in this way."

Under current law, stem cells can only be used to carry out research into fertility, reproduction or congenital disorders, but pressure has been building within Government to expand the legislation to tackle disease and organ transplant problems. Both the Human Fertilisation and Embryology Authority and the Human Genetics Advisory Commission have already recommended that the law should be relaxed to allow therapeutic cloning.

Professor Donaldson was called in last year to head an advisory group on the issue. Lord Sainsbury of Turville, the Science minister, made clear last month that his own personal preference was to give cloning the go-ahead.