David Steel, the former Liberal leader and architect of the 1967 Abortion Act, has lobbied ministers to vote against a bill to change the counselling system for women who want terminations.
Lord Steel, who has talked of the need to amend his original legislation to limit late abortions, said that there was no need for the proposed amendment to the health and social care bill, which MPs will vote on this week. He has written to key figures in the government to urge them to reject it.
The amendment, put forward by the Tory MP Nadine Dorries, would strip established abortion providers and charities of their role as counsellors to women with unplanned pregnancies. Critics say the move would create a gap that would be filled by religious anti-abortion charities and medical professionals.
Steel said: "Under the Abortion Act, the Department of Health has complete power over licensing and de-licensing clinics. If there were any evidence of failure to carry out proper counselling of patients, they can close clinics. More positively, there is nothing to stop them issuing guidelines on counselling if they think that necessary. There is no need to amend the health bill."
Dorries has emerged as the figurehead of the "right to know" campaign that has emerged in the run-up to the vote. Her amendment is almost certain to be rejected this week after the government indicated it did not have the support of David Cameron or the Department of Health. But there is unease among pro-choice campaigners that a US-style anti-abortion agenda is starting to take root in the UK, supported by American Christian evangelical movements.
Ann Furedi, chief executive of BPAS (formerly the British Pregnancy Advisory Service) said: "Over the past couple of decades, anti-choice organisations in the US have moved away from arguing about the morality of abortion, towards presenting their cause in the language of women's health. This often leads them to promote misinformation – for example, that abortion causes breast cancer, infertility or mental illness – as a means of scaring women about abortion, or encouraging legislators to restrict access to abortions. There are important moral and political arguments that should be had about abortion; hiding behind non-evidence based, pseudo-scientific health claims reveals the moral bankruptcy of some anti-abortion campaigns today."
She added: "The Dorries amendment – tagged on to a bill which has nothing to do with abortion – seems to be an example of using legislation to interfere with women's access to a legal abortion service, with the goal of making the experience more unpleasant."
Other providers are worried they may have to take on a new role. "We are not the place for moral or political arbitration," said one pregnancy counsellor. "Our job is to support women and make sure they are making the right decision for them. The last thing I want is to have to spend my time defending the rights and wrongs."
The Royal College of GPs and the BMA have said they do not see any reason for the amendment. Any GP who has an ethical or religious object to abortion is allowed to "conscientiously object" and take no part in referring or treating a woman with an unplanned pregnancy.
Dr Peter Saunders, of the Christian Medical fellowship, which has more than 4,500 doctors as members, said GPs were the right people to give independent counselling. "They would not need to state their own ethical position until it gets to the point that the woman says she would like an abortion and then the doctor can explain to her that they are not able to help," said Saunders, who has advised Dorries.