Health Minister Simon Harris revealed that that a "potentially considerable number of cases" where women developed cancer were not subjected to an audit.
Chair of the HSE Serious Incident Management Team, Patrick Lynch, today said that 17 women affected by the CervicalCheck controversy had died. The figures came to light after terminally-ill mother Vicky Phelan settled her case.
When asked about her decision not to sign a confidentiality clause as part of her settlement, she said: "I was never going to sign a confidentiality clause and that was before I ever knew there were other women involved.In the back of my mind I probably thought there were other women involved but I never knew on this magnitude".
During her appearance Ms Phelan also questioned Mr O'Brien's assertion that he only heard of her case via news reports.
Ms Phelan has said she does not believe Mr O'Brien learned about her case last week.
He was informed that the National Screening Service and the Head of the National Cancer Control Programme had advised the Department in writing that they did not consider this to be a "patient safety issue" but rather a reflection of the known limitations of the current screening test.
Ms Phelan (43), from Limerick, was diagnosed with terminal cancer three years after her smear test results of 2011 were incorrectly reported as clear of abnormalities.More news: Windy, warm Tuesday in Oklahoma, severe weather possible
Several inquiries are due to take place into how 17 women died who had been screened for cervical cancer.
'Cancer screening programmes, offered through the HSE's National Screening Service, aim to detect cancer as early as possible, leading to better treatment options and outcomes for patients.
Mr Harris said he is now moving towards establishing a commission of investigation to uncover the extent of this controversy.
Deputy Donnelly said, "It's completely unacceptable that women affected by these screening errors continue to be left in the dark". He said a liaison nurse will coordinate with the women.
More than 2,000 women have called the CervicalCheck helpline over the weekend.
A helpline, which has been established by the HSE, has received more than 6,000 calls.
The HSE has said it will provide further information and updates over the coming days on cervicalcheck.ie and anyone with concerns may contact the CervicalCheck information phone line on 1800 45 45 55.