Lord Steel, architect of the 1967 Abortion Act, says today that abortion is being used as a form of contraception in Britain and admits he never anticipated "anything like" the current number of terminations when leading the campaign for reform.

The Liberal Democrat peer, whose bill legalising abortion in certain circumstances marks its 40th anniversary on Saturday, says an "irresponsible" mood has emerged in which women feel they can turn to abortion "if things go wrong".

"Everybody can agree that there are too many abortions," he says in an interview in today's Guardian, calling for better sex education and access to contraceptive advice and a debate over sexual morality to help bring the numbers down.

There were almost 194,000 terminations in England and Wales last year, rising to over 200,000 when women coming from Northern Ireland and the Irish republic are included. That was almost 4% up on the previous year, with abortions among teenagers the fastest rising group.

The figures were described yesterday by Catholic church leaders as "a source of distress and profound anguish for us all", in the run-up to likely attempts by both pro- and anti-abortion campaigners to reform the current law this autumn.

Lord Steel, who endured threats of violence and sacks of hate mail when pushing through his private member's bill as a young MP 40 years ago, makes clear he has "no regrets" over the landmark legislation, and does not regard restricting access to abortion as the answer to the rising number of terminations.

He says he is not yet persuaded that the upper legal time limit should be cut from its present 24 weeks - a limit endorsed by the BMA and other medical bodies - and believes there is a strong case that the requirement for two doctors' signatures in order to have an abortion should be dropped in the first 13 weeks of pregnancy in order to limit delays and distress.

He conceded yesterday that the Archbishop of Canterbury, Dr Rowan Williams, "had a point" in warning in an article in last Sunday's Observer that abortion is now being treated as too easy to obtain.

Lord Steel said: "I accept that there is a mood now which is that if things go wrong you can get an abortion, and it is irresponsible, really. I think people should be a bit more responsible in their activities, and in particular in the use of contraception."

He says a lack of research into the reasons women choose to have an abortion is hampering efforts to tackle the problem of rising numbers. But, asked whether abortion is being used in some cases as a form of contraception, he said: "I am afraid it is."

He added: "At the moment we are all operating in the dark. But I think there is a view that particularly those who present for repeated abortions are treating it as 'long stop' [back-up] contraception." Parliament never intended the law to be used in that way, said Lord Steel, who brought his legislation in an effort to save the lives of pregnant women dying at the hands of back street abortionists or by suicide.

He wants improved sex education in schools covering both sexual ethics and the use of contraception.

But he said the Catholic church's opposition to contraception "is absolutely contributing to the use of abortion as contraception".

Lord Steel's comments, in which he effectively qualifies the gains brought by his legislation, provoked surprise and frustration from women's health campaigners. Ann Furedi, chief executive of BPAS, the UK charity providing abortion and contraceptive care, said: "There are many positive reasons why abortion numbers can increase - because women are more easily able to access the services they need, because more abortion care is funded by the NHS, and because more women now believe abortion is an acceptable option if they are faced with an unintended pregnancy.

"If you are opposed to abortion in principle, these changes will be unwelcome, but if you believe that women should be able to make decisions about their reproductive future, then these are positive changes.

"Of course its better to prevent an unwanted pregnancy than to end one in abortion. I've never met a woman in a BPAS abortion clinic who didn't want to not be there. No woman aspires to have an abortion.

"But abortion is not in itself the problem. The problem is the unwanted pregnancy and abortion can be the solution to that for many women. There's no right or wrong number; we need as many abortions as are necessary to solve the problem pregnancies that women face."

She added: "We see parenthood completely differently now - it is not something you drift into because a condom slipped any more. We spend a lot of time worrying about parenting. Women today feel much more strongly about being able to plan when and whether to become a mother."

Lord Steel's comments come as the debate over abortion in Britain reaches its highest pitch in years.

Public health minister Dawn Primarolo is expected today to tell a Commons science and technology committee inquiry into scientific developments affecting abortion that she sees no evidence of the need to reduce the 24-week limit.

That view is shared by medical leaders, including the BMA, the Royal College of Obstetricians and Gynaecologists, and the Royal College of Nursing.

The MPs' committee will also examine the question of whether women should still need to obtain two doctors' signatures to secure an abortion in the first three months of pregnancy.

Polling released yesterday by the pro-choice group Abortion Rights suggests a slight majority - 52% - of the public support liberalisation of the law to require the permission of only one doctor or none.

The NOP poll also showed 83% of the public believe it is a woman's right to decide to have an abortion, with only 13% saying they thought a woman should not have this right.

Changes to restrict or liberalise access to abortion could come via amendments to the human tissue and embryology bill, which is due to come before parliament within weeks.

In an open letter to the British public, cardinals from the Catholic church sidestepped the issue of the law, saying the abortion rate could fall dramatically if enough hearts and minds were changed.

The letter outlined several ways that institutions and individuals could effect a drop in numbers, including offering more sympathetic counselling for pregnant young women, dismantling the "conveyor belt" that could take a young woman through to having an abortion without a thorough exploration of alternatives and providing more and better facilities for young women who choose to have their babies.

The letter, signed by Cardinal Cormac Murphy O'Connor and Cardinal Keith O'Brien, said: "The 1967 Act was intended to solve the problem of illegal abortion, on the basis that it was a major cause of death in pregnant women. Yet our countries now perform nearly 200,000 abortions every year.

"Whatever our religious creed or political conviction, abortion on this scale can only be a source of distress and profound anguish for us all. There is nothing to stop our society from acting now to foster a new understanding and approach to relationships, responsibility and mutual support."