Most GPs think the law should be changed to allow women easier abortions within the first three months, without having to get the written consent of two doctors, according to a survey from the family planning organisation, Marie Stopes International.
The findings represent "a sea change" since the last significant survey of GPs 26 years ago. At that time, only 24% supported a change in the law which would effectively make abortion available "on demand" - at the request of the woman - within the first trimester of pregnancy (14 weeks).
Marie Stopes and other campaigning organisations consider Britain's abortion law, enshrined in the 1967 act, to be outdated, illiberal and bureaucratic compared with the regulations elsewhere in Europe. Many countries now have abortion on request in the early stages of pregnancy.
GPs are the gatekeepers of the 1967 act, says Marie Stopes. He or she is usually the first port of call for a woman who has an unwanted pregnancy and his attitude is critical as to whether she gets a termination and how she feels about the difficult decision she has to make.
The vast majority of the 8,000 GPs contacted for the survey (82%) said they were "broadly pro-choice" and 60% supported changing the law so that a woman's request to a doctor in the first trimester for an abortion would suffice.
Most doctors (84%) said they thought a GP who had a conscientious objection to abortion should be obliged to declare it to a woman who wanted a termination. But 10% of GPs did not agree. Of the 118 doctors answering the question who said they were anti-abortion, nearly 27% thought they should not have to tell the woman of their convictions.
This worries Marie Stopes, which points out that just under 5% were both anti-abortion and reluctant to declare their position. "If this was reflected nationally, out of a population of approximately 35,000 registered GPs, we might estimate that around 1,680 GPs nationwide may be actively working against the 1967 abortion act and preventing women's access to abortion on spurious legal grounds," says the report.
Helen Axby, deputy chief executive of Marie Stopes International, said the report showed abortion in Britain today was "a complete lottery - arbitrary, discriminatory and unfair.
"MSI is encouraged by the strength of support from GPs for reform, to introduce a modern law where the decision on abortion rests with the woman concerned - in consultation with a doctor. At the moment the woman is at the mercy of two doctors exercising discretionary powers.
"We are disturbed by the finding that a small, but significant minority of GPs may be imposing their own moral standards and values upon women, causing distress, delay and financial hardship."
Mike Pringle, chairman of the Royal College of General Practitioners, welcomed the information about GPs and terminations contained in the report.
"We support a woman's right to make considered decisions within the limits of the law and believe general practitioners should have the right to choose their stance as long as it does not affect a woman's right to choose or access services," Professor Pringle said.