Brown launches defence of embryo research as British public demands test-tube babies 'have the right to know their fathers'

Gordon Brown staged an impassioned defence of human-animal embryo research today, insisting it could save millions of lives.

As the Commons prepares for a crunch vote, the Prime Minister said developing "hybrid" techniques was an "inherently moral endeavour".

MPs owed "to ourselves and future generations" to pass measures permitting the use of such embryos, he argued.

But the PM's controversial plans to exclude all mention of fathers from the law covering test-tube babies has been overwhelmingly rejected by the British public.

The majority of people believe that a child has a right to male and female parents and to know the identity of its biological parents.

But these rights will be swept away if the Prime Minister wins a key Commons showdown on Tuesday when MPs vote on the Human Fertilisation and Embryology Bill.

Mr Brown faces a rebellion, with 20 MPs, including 12 from his own party, signing an amendment that would restore a child's right to a father and a mother.

Many more Tory and Labour MPs are expected to support the rebels now that all MPs have a free vote on the issue.

The strength of public opposition to Mr Brown's plan is revealed in an independent YouGov opinion poll commissioned by the Centre for Social Justice think-tank (CSJ), chaired by former Tory leader Iain Duncan Smith.

The survey found that eight out of ten people believe a child has a right to two parents and that six out of ten believe that a child should have male and female parents.

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The present law states that fertility clinics must take account of a child's need for a father when assessing women for treatment.

This means that when a single woman or lesbian or gay couple apply for fertility treatment, the clinic cannot ignore the role fatherhood plays in a child's welfare.

Opponents of the Bill warn that, amid mounting evidence of the damage done by absentee fathers in terms of crime, anti-social behaviour and school failure, now is not the time to send an official message that fathers don't matter.

They also point out that existing sex discrimination laws make it illegal to reject a lesbian couple applying for IVF treatment on the basis of their sexual orientation.

Mr Duncan Smith said: "This move by Gordon Brown has huge symbolic significance. It will not make any practical difference to lesbian and gay couples but, if passed, it will send a dismissive message about the family and about the importance of fathers in the upbringing of children.

"We should be including fathers in, not including them out."

Over two days of debate, MPs will also vote on moves led by Tory MP Nadine Dorries to reduce the upper limit for abortion from 24 to 20 weeks and to legalise animal-human hybrid embryos for medical research as well as so-called 'saviour siblings' – children whose body tissue can be used to help a brother or sister with a serious illness.

The poll is part of a CSJ report called Fathers Not Included, which also condemns Government moves to remove from birth certificates all reference to the biological parentage of children.

They will be registered as having two mothers or two fathers and will not know who brought them into the world.

The report says Ministers want to change the law to appease the gay lobby but it points out that fewer than 2 per cent of IVF treatments in 2006 were for single or lesbian women.

It says the Government is flying in the face of a wealth of social research showing how important committed fathers are to families and communities.

It warns: "By ignoring the benefits fathers bring to children in order to accommodate childless adults, the Bill places the rights of adults at the centre, rather than the best interests of children." The report recommends that the role of fathers and mothers should be formally recognised and protected by a clause within the Bill and that further research should look at the outcomes for children born by donor conception and raised by same-sex couples.