Up to 6,000 women in the Republic of Ireland are likely to be informed their cervical smear tests will have to be repeated, according to the Health Service Executive (HSE).
It follows an identification of an issue with HPV tests.
There are delays to both routine and repeat tests, due to the demand. As a result of the backlog, some original tests have expired.
The health minister said 0.29% of tests expired from April to October 2018.
A spokesperson said this was not significantly higher than the previous year.
The minister, Simon Harris, announced in April that a free test would be made available to any woman who wanted one following the CervicalCheck controversy.
About 220,000 women get a smear test each year in the Republic of Ireland, but 108,000 extra availed of the service last year.
Tests to be processed 'as a priority'
Dr Peter McKenna, Clinical Director at the Women and Infant's Health Programme, said women will be recalled as a precaution.
"Our clinical review has assured us that this issue poses little risk to women's health," said Dr McKenna.
Today, I called on the Minister for Health to make a statement after it emerged how the unnecessary extra cervical checks offered by the Government without an increase in resources, have caused backlogs to the point of tests expiring. pic.twitter.com/quTu6oECwl— Micheál Martin (@MichealMartinTD) January 23, 2019
"Evidence shows that HPV tests of this kind are effective outside the manufacturer's recommended timeframe.
"Based on our current assessment of the information provided by Quest (the laboratory), we expect that up to 6,000 women will likely be called for a repeat smear test. These tests will be processed by the laboratory as a priority," he added.
Failures in Ireland's cervical cancer screening programme meant that at least 208 women diagnosed with the cancer should have received earlier intervention.
Some of them have since died, including Orla Church and Emma Mhic Mhathúna.
Fianna Fáil leader Micheal Martin told the Dáil (Irish parliament) on Wednesday that the decision to offer tests to all women had resulted in an "enormous" demand on the CervicalCheck screening program.
Mr Martin said that had now left the entire programme in "jeopardy".
"The additional volume of tests as a result of the decision taken has created enormous and unacceptable backlogs and women have been waiting up to six months for the return of their tests," he said.
"There is a further problem; it is my understanding that the delay has impacted on the quality and efficacy of the tests, rendering a significant number of them invalid."
Mr Harris said the decision to offer free smears to all women was taken collectively by government and followed demand from GPs, as well as thousands of women, who had contacted a helpline set up in light of the CervicalCheck controversy.
More than 220 women and their families have been affected by the CervicalCheck crisis.
They received incorrect smear test results, which were discovered during a clinical audit of the screening programme.