Pioneering new smear tests are no more reliable than the conventional test for checking for signs of cervical cancer, scientists have said.
A review of the liquid-based cytology (LBC) test by researchers in medical journal the Lancet revealed that the test did not detect any more serious abnormalities which could lead to cancer than the older smear test.
It was also found they did not cut the rate of tests which yielded false results
Despite the findings NHS experts have said the new tests cut unusable results by 90 per cent in England.
The Scottish Executive said it would look at the Lancet findings, but its health department said it had so far found that the LCD tests were far more accurate at screening for cervical cancer than the traditional smear test.
The LCD test is taken like a traditional smear test but uses a brush and deposits cells from the cervix in liquid to remove any obscuring material before the cells are tested for abnormalities.
The traditional smear test, or Pap smear, as it is known, deposits the cells straight on to a slide for testing without removing any surrounding debris.
Previous reports claimed the new method increased the sensitivity of the tests and cut the number of unclear or false results.
However, in a review of 56 studies involving over one million slides, researchers from Sydney University in Australia found no evidence that the LCD method was more reliable at detecting signs of cervical cancer that the conventional Pap smear.
Lead researcher Dr Elizabeth Davey said, however, that the test could have economical advantages.
She said: "Although we did not find liquid-based cytology to be more accurate than conventional cytology equivalent performance might be sufficient if liquid-based cytology has other advantages such as the opportunity for concurrent HPV DNA testing, reduces reading times or is more economical than conventional cytology."
Calling the study "interesting", Dr Anne Szarewski, clinical consultant at Cancer Research UK, nevertheless said the findings "do not tally with the experience of using liquid based cytology screening" in Britain.
"In the UK a number of large-scale pilot studies have been conducted to assess the benefits of liquid based cytology screening," she said.
"In all of these studies there has been a significant reduction in the proportion of unsatisfactory slides and therefore a fall in the number of, often unnecessary, repeat tests.
"In addition, the time required to read the slides and the fact that other tests can be done from the same specimen, adds to the benefits of the liquid based cytology method compared to the conventional smear test."