Taoiseach Enda Kenny has told the Dáil "words don't exist to adequately address the depth and volume of revulsion" felt over allegations of abuse in a foster home in the southeast.
He was speaking during statements on the establishment of a Commission of Investigation into a former foster home in the region.
Mr Kenny said that if William Butler Yeats had said Ireland was no country for old men, it had been "positively treacherous for our girls and women".
The case centres on an intellectually disabled non-verbal young woman, known as 'Grace', who was left in the home for more than 13 years after it became the subject of abuse allegations.
He said a Commission of Investigation was the "right way to address" the enormity and depravity of what had been uncovered at the foster home.
'Was the system blind? Was the system deaf?' Enda Kenny expresses revulsion over southeast foster home allegationshttps://t.co/MLKxwk5cFZ— RTÉ News (@rtenews) February 2, 2016
"Those who left her to her fate pressed the mute button on her young life and her appalling experience," Mr Kenny said.
"Above all the mute button was pressed on her dignity, her humanity, on her civil and human rights."
He added: "Was the system blind, was the system deaf? Did the system possess so little awareness and so little accountability that it could become a stone to Grace?
"The Commission of Investigation, I expect, will answer these questions. It will get the answers the people need."
Mr Kenny added the next government would have to approve and proceed with the inquiry.
Earlier, HSE Director General Tony O'Brien told the Public Accounts Committee he is concerned other cases similar to the alleged abuse in the southeast may have happened elsewhere in the country.
Later, speaking on the Six One, he said: "Knowing the history that we have as a country in various contexts, it would be very foolish of me to suggest that there can be an assurance that what happened in the southeast in the 1990s didn't happen anywhere else."
At the PAC meeting, Mr O'Brien also said he has “serious questions in his mind” about the decision to leave 'Grace' in the foster home in question.
Mr O'Brien said the decision was made by a three-person panel but added that none of the three are still in public service.
There is substantial information relating to that decision in one of two unpublished reports on the matter but he could not legally stray into that, Mr O'Brien said.
PAC member and Fine Gael TD John Deasy accused the director general of "stonewalling" the Committee and hiding behind the unpublished reports.
Mr O’Brien said he would answer any questions he was able to but stressed the matter remains "subject to a live investigation" by gardaí and he did not want to "prejudice or to impede that process".
"It is clear from both of the unpublished reports that there were significant failings in the care provided by that foster family and significant failures by the former Health Board and subsequently the HSE to make the situation safe," Mr O'Brien added.
"For this, I offered them and their family members a full, sincere and heartfelt apology," he said.
From April 2015: the RTÉ Investigation that revealed the southeast foster-care scandal https://t.co/td9JUNjCM3— RTÉ News (@rtenews) February 2, 2016
He said the cost of the two reports amounted to €225,000 - not including legal costs.
This afternoon, Mr O’Brien also apologised for unintentionally misleading the PAC about whether an apology had been issued to ‘Grace' and her mother.
Last Saturday, the HSE accepted that no official apology had been issued to the woman as had been previously stated by the executive.
Mr O'Brien told the committee that a verbal briefing was to be given to ‘Grace’ and her mother on the 10 December but the HSE "mishandled" the letter of apology.
He said the HSE then decided to apologise verbally in person, however he told the committee that it is now clear that the apology was never offered and was not instructed to HSE staff.
He said it was the intention to offer a full and frank apology to 'Grace'. He said an apology has since been made in person and in writing to 'Grace'.
Mr O'Brien said he is unhappy with the way the HSE mishandled the apology and he offered families involved "a full, heartfelt and sincere apology."
He added that the HSE will not challenge any legal actions taken against it by former residents of the foster home.
Plans for a Commission of Investigation into the abuse allegations were due to be discussed by Cabinet today.
"I welcome such a Commission as it would provide a statutory mechanism in order to conclude this drawn-out process and allow the 47 service-users, their families and other interested parties to get answers to the questions that they have been asking for many years now on this deeply concerning and dreadful case and to achieve some level of closure for all concerned," Mr O'Brien said.
Mr O’Brien also said from 1995 there were no new placements at the foster home by the health service.
However 'Grace' remained in care there under the direction of the health service until 2009.
Another young woman with an intellectual disability, known as 'Ann', also stayed at the home on a part-time basis after the concerns were raised, he said.
'Ann', now aged 35, visited the foster home on a privately-arranged basis since 1992 as a 12-year-old and continued to do so until a HSE request to cease the fostering arrangement in late 2013.
Chairman of PAC John McGuinness said the abuse dates back for years and authorities were contacted by officials in the UK in the mid-90s after a family who had experience of the home made their concerns known.
He said the Brothers of Charity stopped making referrals in 1990 because of concerns about the care.
Mr McGuinness said that at any given time no one knew how many people were in the house and it was never inspected.
Whistle-blowers made concerns known in 2009
He told RTÉ's Today with Sean O'Rourke whistle-blowers made their concerns known to gardaí as far back as 2009.
A letter, dated 24/11/2014, was sent to the HSE’s national director of quality and patient safety outlining concerns in detail but there has never been a reply to that letter, he said.
A protective disclosure was made to Mr McGuinness by one whistle-blower and he in turn made a protective disclosure to the gardaí last year.
He added the HSE has resisted every attempt to expose fully what allegedly happened since it has come to light, adding that people in the HSE know what happened and they should make the information public.
Earlier, Chief Executive of the Children's Rights Alliance Tanya Ward welcomed plans for a Commission of Investigation saying the Government of the day should approve it and provide funding for it.
Speaking on RTÉ's Morning Ireland, Ms Ward said there is no reason why the HSE should not do its own internal investigation in relation to practice and there is no reason why those people cannot be disciplined.
She said the Commission will have to ask if the appropriate law and procedures were in place to protect the children and women.
She said it will have to establish what harm came to these people and if this was preventable and how did the HSE and other authorities including the gardaí respond.
She said the Commission of Investigation must ask if they responded effectively or if they waited too long and also establish why it took the PAC to uncover this.
She said the confidence of people with intellectual difficulties and people within the care system has been knocked by these incidents.