Over half of GPs (52%) believe the agreement of one just doctor should be enough for an abortion in the first 14 weeks of pregnancy, a survey shows.
Two doctors have to agree to a woman having an abortion
At present a woman must persuade two doctors that carrying on with the pregnancy is a health risk.
However, the Marie Stopes survey of 1,000 GPs also showed two-thirds wanted the current 24-week time limit for abortion to be reduced.
The government said there were no plans to change the law on abortion.
The survey showed that 80% of doctors support the right to abortion - but one in five describe themselves as "anti-abortion".
Three in five doctors polled said current guidelines allowing under 16s to access abortion without the consent or knowledge of their parents were "satisfactory".
The survey also found most doctors were in favour of being able to have free abortions on the NHS.
However, the majority in favour of a reduction in the time limit for abortion contradicted with previous research showing most doctors support the current limit, which is also backed by the British Medical Association, the Royal College of Obstetrics and Gynaecology and Royal College of Nursing.
The survey also found an increase in the number of GPs who did not think that they should be obliged to declare any conscientious objection to abortion to patients.
Marie Stopes International said it was concerning that a significant minority of doctors could be actively blocking women from accessing abortion services.
October marks the 40th anniversary of the introduction of the 1967 Abortion Act.
This summer, the British Medical Association conference backed a motion calling for abortions to be approved by just one doctor.
Liz Davies, of Marie Stopes International, said the current two-doctor rule was "archaic".
"Contrary to popular belief, we do not currently have abortion on request in Great Britain, unlike most other European countries, and reform is long overdue.
"Women should not be forced to justify their choices, but should be trusted to make the right decision and assisted by doctors to access appropriate services."
Julia Millington, of the ProLife Alliance, said: "With many doctors routinely failing to comply with the current law, it is hardly surprising that they would like the burden of responsibility for the annual abortion of 200,000 unborn children taken from them.
"With abortion provided on demand in the UK and annual figures escalating, we should surely be seeking ways to reduce this tragic loss of life and providing better solutions for women in crisis pregnancy situations."
A spokesperson for the Department of Health said: "The government has no plans to change the law on abortion."