The researchers who established its potential say it could improve the chances of preventing cancer in developing world.

At the moment, five per cent of women in the developing world are screened for cervical cancer. In industrialised nations the figure is 70%.

Vinegar - acetic acid - could be used where the standard Pap smear is unavailable or too expensive.

In the UK, the NHS Cervical Screening Programme estimates that testing for early signs prevents up to 3,900 cancers each year.

Basic technique

Researchers from Johns Hopkins University and the University of Zimbabwe conducted a study of the method's effectiveness.

They publish their findings in The Lancet medical journal.

Dr Paul Blumenthal, of Johns Hopkins, said: "This technique easily could be used by health care workers in areas with limited resources.

"It could have a tremendous impact. What this test offers is the promise of prevention to women who might not otherwise have been able to access a screening test.

"What we are looking for is cases of pre-cancer and that is virtually curable and will prevent cervical cancer."

The researchers evaluated the vinegar screening test in a study of 10,000 women at 15 clinics in Zimbabwe. They concluded it was safe and effective.

Visual inspection

The test involves a visual inspection of the cervix as opposed to sending a sample to a laboratory.

Usually a sample is taken and sent to the lab . . .

The women were screened using both the acetic acid test and the traditional method. The researchers found that both techniques had a similar detection rate.

It could help health care workers make an instant decision as to whether a patient needs further treatment.

This is an important factor in areas where women live far from medical facilities.

Cervical cancer is one of the most common cancers affecting women, killing 200,000 each year.

. . . where scientists examine the cells for signs of pre-cancerous changes

It is the leading cause of cancer deaths in parts of Africa, Asia and Latin America.

The earlier it is detected, the better the chances of defeating it. If it is caught before it spreads beyond the cervix, 95% of cases are curable.

Cervical cancer is caused by the human papilloma virus and the Pap smear is the most widely used screening technique to detect it in the UK.

Pap smears are where a sample is take from the cervix, and then smeared on to a slide for examination.

The cells on the slide are then examined for identifiable pre-cancerous changes.

This process often collects blood and inflammatory tissue that can obscure the important cells pathologists need to examine.

Range of screening techniques

Pathologists are looking for new techniques to improve accuracy, particularly after a series of highly publicised errors in the UK screening programme.

Liquid-based cytology a technique used in the US. The whole sample is placed in solution and transferred to the laboratory. There it is prepared on a slide.

The resulting slide is free of blood and inflammatory tissue and offers a more representative sample of cells.

However, this technique is yet more expensive than the Pap smear.

The vinegar technique is extremely cheap by comparison.

The doctors simply wash the cervix with dilute acetic acid and then inspect it by eye.