About 1,000 women have been called back to a North East surgery to have repeat smear tests amid concerns that tests taken over the past 24 years were botched, health officials have said.
NHS County Durham and Darlington has traced the patients, some of whom were tested as early as 1988, after it emerged that tests conducted at a County Durham practice were flawed.
It has apologised and urged those affected not to panic, saying it is unlikely that any cases of cervical cancer will have slipped through the net.
Anna Lynch, the organisation's director of public health, said: "Through our quality assurance process, we identified that some cervical smear tests taken at Bewick Crescent Surgery in Newton Aycliffe may not have reached a satisfactory standard.
"As a precaution, we have written to approximately 1,000 women inviting them to attend for a repeat test to confirm the results of their original test.
"The risk that any cervical abnormalities have not been picked up is very low, but as a precaution we have invited the women involved to attend for a repeat test and have set up extra appointments so they can be seen quickly. We have also arranged for their results to be available within two weeks of their test."
She added: "I would like to apologise to those women involved for any inconvenience or concern that this recall has raised, but would like to reassure them that this decision was taken in their best interests, is purely a precautionary measure and the risk to those women is very low."
NHS County Durham and Darlington said it had followed national guidance from the Department of Health, adding: "Our investigation has looked back to 1988, which is when the national screening programme was first introduced.
"The primary care trust, in managing the recall, has followed a very comprehensive and stringent process to make sure that we are not inviting any women back unnecessarily. A proportion of women have been excluded from the recall because they do not need another cervical screening test."