Two Roman Catholic bishops in Ireland resigned on Christmas Day in the wake of a damning investigation into decades of church cover-up of child abuse in the Dublin archdiocese.

Dublin Bishops Eamonn Walsh and Ray Field offered an apology to child-abuse victims as they announced their resignations during Christmas Mass. Priests read the statement to worshippers throughout the archdiocese, home to a quarter of Ireland's 4 million Catholics.

Earlier this month two other bishops, Donal Murray of Limerick and Jim Moriarty of Kildare, quit following the Nov. 26 publication of a three-year investigation into why so many abusive Dublin priests escaped justice for so long.

The government-ordered investigation found that Dublin church leaders spent decades shielding more than 170 pedophile priests from the law. They began providing information to police only in 1995 _ but continued to keep secret, until 2004, many files and other records of reported abuse.

In a joint statement Walsh and Field said they hoped their resignations "may help to bring the peace and reconciliation of Jesus Christ to the victims (and) survivors of child sexual abuse. We again apologize to them."

"Our thoughts and prayers are with those who have so bravely spoken out and those who continue to suffer in silence," the bishops' statement said.

The Dublin archdiocese has faced a rising tide of civil lawsuits from abuse victims since the mid-1990s, after one abuse victim, former altar boy Andrew Madden, went public with the church's effort to buy his silence and protect a serving priest. The archdiocese estimates its ultimate bill for settlements and legal costs may top euro20 million ($30 million).

A fifth serving bishop named in the investigation, Martin Drennan of Galway, insists he did nothing to endanger children and won't resign _ the line initially adopted by the other four bishops, too.

"Martin Drennan will have to resign. We want full accountability," Madden said. He criticized the bishops' initial position that "as a group they were very apologetic, but individually they had done nothing wrong."

Archbishop Diarmuid Martin, a veteran Vatican diplomat put in charge of Dublin in 2004 with a brief to confront the abuse scandal, welcomed the resignations. Walsh had been a bishop since 1990, Field since 1997.

Martin said in an interview that the church "must ensure that the management of the past is entrusted to a new generation of people who think differently."

Earlier, in his Christmas sermon, Martin said the church for too long placed its self-interest above the rights of its parishioners, particularly innocent children.