Lord Steel, the architect of the law that legalised abortion, today called for measures to make it simpler for terminations to be carried out "as early as possible".

Speaking on the second day of the Global Safe Abortion conference, the former Liberal leader said that there were "too many abortions" and a lack of research into the reasons behind the rise.

The number of abortions in England and Wales stood at 193,700 in 2006, compared with 186,400 in 2005, according to the latest available figures.

In the year following the Abortion Act 1967 there were 55,000 abortions in the UK.

Lord Steel said: "Abortion should not be regarded as long-stop [back-up] contraception, and, as a society, we need to address these issues, as well as the questions of sexual ethics and sex education."

But he went on to say that there was "no such thing" as a correct number of abortions.

In a speech marking the 40th anniversary of his bill to legalise abortion, the Lib Dem peer said that the current inquiry by the science and technology select committee into the 24-week abortion limit should address barriers to ensure that as many terminations as possible took place within 13 weeks.

"I have always argued that, if abortion is sadly necessary, it is desirable that it should be carried out as early as possible," Lord Steel told the conference.

"Many argue that the two-doctors requirement causes undesirable delay, and, since 1967, many of our European neighbours have legislated for abortion up to the 12th and 13th week of pregnancy without such a requirement. The committee should address that."

He added that the 1990 decision to reduce the original 28-week limit to 24 weeks was taken in light of new medical techniques.

On the case for reducing this further, he said: "There needs to be convincing evidence of viability earlier than that to justify a further change; improvements in photographic technique are not themselves sufficient.

"As it is, very few are carried out after 22 weeks, since we all agreed that is undesirable."

Earlier today, Dawn Primarolo, the junior health minister, said that there was no reliable medical or scientific evidence to justify a further reduction.

Asked by Phil Willis, the chairman of the science and technology committee, whether the law needed to be changed to remove barriers that prevented abortions being carried out in the first three months, Ms Primarolo said figures showed that the NHS was already performing the overwhelming majority of abortions (89%) in the first 13 weeks of pregnancy.

Pilot experiments involving the delivery of medical abortions - whereby pregnant women take medication to trigger an abortion - by nurses, rather than doctors, were already under way, the committee heard.

The influential committee is examining recent scientific evidence on issues such as the long-term impact of abortion on the mother's health and whether babies born younger than 24 weeks can survive.

On the existing 24-week abortion limit, Ms Primarolo was questioned by MPs about the survival rates of babies born at 21, 22 and 23 weeks.

Nadine Dorries (Con, Mid Bedfordshire) told the minister: "If you look at individual units where there are good neonatal units, the rates [of survival] are much higher. Do you still feel 24 weeks is the right limit?"

Ms Primarolo explained that the Department of Health was informed by evidence from respected medical and scientific bodies, including the British Medical Association and the Royal College of Obstetricians and Gynaecologists (RCOG): "We are looking at the [medical] consensus quite clearly and the figures we already have."

Ms Primarolo said that any changes to the existing limit would have to be "for the House [of Commons] to decide".

Ms Dorries - who last night suggested that the RCOG might have deliberately submitted misleading evidence to the inquiry - challenged Ms Primarolo on whether her calls for a liberalisation of abortion law made her "the right minister for the job".

Ms Primarolo replied: "I do not have to discuss my personal views. I am here as a minister to answer questions that the committee puts to me about the information the department has. I am perfectly capable of giving that information where I have it." Ms Dorries pre-empted today's committee hearing by accusing the RCOG of ignoring crucial research supporting the case for a lower limit.

The Tory MP said the body was dominated by advisers who had a "vested financial interest" in keeping the number of terminations high. The inquiry's terms of reference specifically focus on scientific considerations and not ethical and moral arguments.

Abortions after 24 weeks are allowed if there is grave risk to the life of the woman, evidence of severe foetal abnormality, or risk of grave physical and mental injury to the woman.

The MPs' inquiry follows medical advances in the care of premature babies and widespread public interest after the release of 3D images showing foetuses apparently "walking in the womb" at only 12 weeks.

The committee received evidence last week from the British Association of Perinatal Medicine (BAPM) who said initial findings from a major study, the Epicure2 survey, did not support arguments for the cut-off point to be toughened.

The BAPM research was based on babies born at less than 26 weeks in 2006 - 11 years after the first such survey.

In a written submission, it said that while the data was still being analysed, "early indications are that for infants below 24 weeks of gestation, the survival to discharge home was very similar between the cohort of 1995 and that of 2006. Headline figures of approximately 10-15% survival were found".

But another witness, John Wyatt, professor of neonatal paediatrics at University College London, presented the committee with evidence that up to 42% of babies born at 23 weeks at his specialist unit in London survived.

Catholic and Church of England leaders have called for a reassessment of abortion's role in society, in the run-up to the 40th anniversary of the act.

In a letter on Monday, the heads of the Roman Catholic Church in England, Wales and Scotland insisted abortion "robbed everyone of their future" - while accepting that it would never be abolished altogether.

The Archbishop of Canterbury, Rowan Williams, warned at the weekend that the public was in danger of losing its "moral focus" on the issue, and treating the procedure as normal rather than a last resort.

Two years into his political career as MP for Roxburgh, Selkirk and Peebles, aged just 29, the then-David Steel pushed through a private member's bill that resulted in the Abortion Act 1967, succeeding where six previous parliamentary attempts had failed.