The BBC's Daniel Sandford: "It's role is still to be decided"

Researchers found traces of the human papillomavirus (HPV) present in 99.7% of cervical cancer tumours taken from 1,000 women.

It is the strongest link yet between the virus and the disease.

Tests are available for HPV, which could be used either in addition to the current smear test used to detect cervical cancer, or on their own.

But the test is not currently available on the NHS.

A campaign for the introduction of HPV testing is gathering momentum, as HPV test is convenient, less painful and can even be carried out by the woman herself at home.

Other scientists are testing vaccines which could prevent the infection.

Uneccessary anxiety

However, many women carry HPV without ever developing cervical cancer, and there are some fears that a screening test could cause unneccessary anxiety to women who test positive but are not going to fall ill.

Dr Peter Sasieni, from the Imperial Cancer Research Fund, said: "If you had a test that was extremely sensitive to HPV, you would probably identify every woman who was going to get cervical cancer.

Dr Peter Sasieni says HPV testing could cost millions - and still miss cases

"But you would rule out perhaps only two-thirds at most of the women you test.

"Do you want to treat a third of the women in the UK with minor surgery for a disease they may never get?"

He cautioned against a headlong rush into providing HPV testing for all women, particularly if it meant the replacement of the present cervical smear programme.

Test would still miss cases

If used on its own, he said, even the latest test would still miss cases of cervical cancer that would have been picked up by smear testing.

And a "kneejerk" reaction to make the test universally available in conjunction with smears could add millions to the cost of cervical cancer screening, he said.

Instead he called for government funding for pilot projects to test whether HPV testing could work alongside smear testing.

"If all cervical cancer is really caused by HPV, then we could eliminate the disease with a vaccine," he said.

The factors which decide whether a woman with HPV will develop cervical cancer are not yet known, although some doctors believe that a weak immune system, or the presence of a large amount of the virus may contribute.

Certainly it appears that many women who test positive for HPV while young have managed to eradicate the infection naturally when tested later.

Drug company Digene, which manufactures a test for HPV, hailed the study results as a breakthrough.

Evan Jones, its chief executive, said: "The new information demonstrates that HPV infection is perhaps the sole cause of cervical cancer.