The Taoiseach has told the Commission to Inquire into Child Abuse he was "struck by the genuine hurt and suffering" expressed on meeting those who had been abused in industrial schools.
Explaining the motivation behind his public apology in 1999 on behalf of the State to former residents of industrial schools, Mr Ahern told the Commission's investigation committee that the State had left a section of the community "vulnerable and exposed".
He said both he and the-then minister of education, Mr Martin, believed the "hurt" that these people felt was not going to be redressed unless there was an apology.
The Taoiseach said these people had been "badly dealt with by the State and we owed them something".
When asked to explain the meaning behind the apology, Mr Ahern said it was simply to say "The State had let you down".
He told the committee that he first became aware of the abuse in the mid- to late-1990s through meeting individuals who had been abused and through a number of media reports.
He said the question of abuse was formally raised at cabinet level in March 1998 by Mr Martin after which it was agreed to set up a sub-committee to investigate the issue further and to examine records held at ministry of education.
Soon after a "high-powered" inter-departmental working group, which included the heads of several departments, took over the investigation.
This group submitted a report to cabinet in April 1999 recommending a number of measures including the setting-up of a counselling service, the establishment of a commission and adjusting the Statute of Limitations to avoid court actions by survivors being frustrated.
Mr Ahern said the cabinet accepted all the recommendations and set about enacting them as "matter of urgency".
He said the issue of an apology was not contained in the report and that he and Mr Martin felt more had to be done.
He described one meeting with victims' groups in Government buildings in which a number of people were crying, saying "this was not a pretty sight".
Mr Ahern said these were "decent, honest people who deserved the best the State could give".
He claimed it was unusual for the State to make such a "public and wholehearted" apology.
He said he believed the true test of a democracy was how it treated its weakest members and the abuse of any child was a source of "deep personal sorrow" to him.
Mr Colm O'Gorman, spokesman for the One in Fourabuse group, said the Taoiseach's acknowledgement that victims were being honest and genuine was significant.
"The Government failed people when in 1999 they promised things they could never deliver," he said. "What is important is that the Commission now works to establish the scale of the abuse, how and why it happened."
He said the discovery of files held in the Vatican which contained evidence of Irish child abuse between the 1930s and the 1960s was the real "smoking gun".
"The state should now be demanding that all evidence relating to cases of child abuse be handed over," he claimed.
Bur Mr John Kelly, spokesman for the Survivors of Child Abusegroup, branded Mr Ahern's apology "empty and shallow" and said that to say the state had let victims down was an understatement.
"It's clear that the Government chose to focus solely on the counselling and healing of abuse victims rather than trying to bring those who were to blame to justice," he said.
"This is just the easy option. For all of his apologies hardly anyone has been sent to prison for these horrific crimes, there has been no accountability.
