The Commission investigating claims of physical and sexual abuse in childcare institutions over the last 60 years is seeking a three-year extension because of the huge number of victims keen to testify.
According to an interim report published today, the inquiry caseload has doubled.
High Court judge Ms Mary Laffoy said her commission would need an extra three years from May 2002 to hear all the evidence. It had been due to report next year.
"Based on the current case load, the commission will not be in a position to publish its final report until some time in the year 2005 at the earliest," she said.
The number wanting to appear before has doubled to more than 3,000.
Most of the applications have come from Ireland and Northern Ireland. But over a third are Irish people living in Britain, other European countries, the United States, Canada, South Africa, Australia and New Zealand, all of whom are also claiming they suffered abuse as children.
A separate redress body is being set up by the Dáil to award compensation to the victims, which should be jointly funded by the Catholic Church.
Some estimates put the total bill at £300 million. Compensation cases against the church are also before the courts.
The Commission was established after the Taoiseach, Mr Ahern, made an unprecedented apology to victims in 1999 on behalf of the country.
He acknowledged that abuse in state-funded institutions had ruined the childhoods of many people.
The commission is examining allegations surrounding schools, orphanages, children's homes and hospitals dating back to 1940 and, if necessary, earlier. Most were run by the Catholic Church on behalf of the state.
Major inquiries by gardaí into many of the institutions are still ongoing and a number of members of religious orders have been jailed.
Several religious orders have apologised to victims who had been in their care.
AFP