A revolution in the law that governs IVF treatment - which would end the requirement for women to find a man to act as father to their child - was for today by the head of Britain's fertility regulator.

Suzi Leather, chairman of the Human Fertilisation and Embryology Authority (HFEA), said the law should be changed to remove the clause requiring doctors who assess infertile women to take account of the "need of the child for a father" before offering treatment.

It would give the green light to single women and lesbians to seek treatment on equal terms with heterosexual couples. But the downgrading of the father's role in child rearing is likely to be portrayed as an attack on the traditional family. In an interview with The Independent, Ms Leather described the clause that mentions fathers as "anachronistic" and "a bit of a nonsense". It was out of step with other changes in society and with government policy, she said.

She set out her views at the annual conference of the HFEA today that will launch a review of the welfare provisions of the Human Fertilisation and Embryology Act 1990, now widely perceived to be outdated.

The review will cover the background and age of couples, their medical histories and suitability to be parents. It is part of a wider review of the Act, to bring it up to date with advances in science and changes in society in the past decade, which will be presented to ministers by the end of the year.

But Ms Leather's views on the need for fathers are likely to generate the greatest controversy. She said: "It is absolutely clear if you think about the changes in society and the different ways that families can be constituted that it is anachronistic for the law to include the statement about the child's need for a father. It seems to me a bit of a nonsense to have that still in the legislation."

One in four families is now headed by a single parent and many did an excellent job of raising children, she said. Government policy had also moved to recognise gay marriages by the introduction of civil partnership. It was much more important for clinics to assess women on their medical and social circumstances than to consider whether they had a man in tow, Ms Leather said.

"I don't think single and lesbian women should be excluded on those grounds. Those would be inappropriate grounds for withholding treatment in themselves. It is much more important to look at the individual circumstances of couples and women. Obviously, single and lesbian women can make fantastic mothers but this is contentious."

She said she was defending the right of all infertile women to have equal access to treatment. "The biological clock ticks for women in a way that it doesn't for men. It is not fair that women feel they have to grab any passing man in order to pass that test at the clinic."

But she insisted the welfare of the child should remain a central plank in the legislation and moves to remove it by some sections of the fertility business had to be resisted.

"There is a view that infertile couples are being made to jump through hoops and that they should not be discriminated against. I think we owe the greatest duty of care to the children we are creating through the use of these technologies. They can't consent to them and they are profoundly affected by them."

At least half of clinics already offer treatment to single and lesbian women, with three or four operating a definite "yes" policy, according to the HFEA. They can meet the legal requirement if they can demonstrate a father figure will be available to the child in the form of an uncle or grandfather. But a change in the law would be of symbolic importance and send a message to single women that they were entitled to treatment.

Jack O'Sullivan, of Fathers Direct, said although one in four families was headed by a single parent, that did not mean fathers were not involved with the children in those families.

"We are learning more and more from research about the importance of fathers in children's lives. We already know they can have a big impact on social skills of young children, the educational achievement of teenagers and latest research shows they may be very important in adult mental health.

"Fathers matter and it would be a mistake to downgrade that important role. I would be looking for a solution that both emphasised the importance of fatherhood while making fertility treatment as widely available as possible." Peter Hill, of Families Need Fathers, a pressure group that works for separated men, said: "All the indicators are that children who have input from a father do better and suffer fewer emotional problems."