DUBLIN — Bishops of the Roman Catholic Church in Dublin covered up decades of child abuse by priests to protect the church’s reputation, an expert commission reported Thursday after a three-year investigation.

Abuse victims welcomed the report on the Dublin Archdiocese’s mishandling of abuse complaints against its parish priests from 1975 to 2004. It followed a parallel report published in May into five decades of rape, beatings and other cruelty committed by Catholic orders of nuns and brothers nationwide in church-run schools, children’s workhouses and orphanages from the 1930s to mid-1990s.

The government said the Dublin investigation “shows clearly that a systemic, calculated perversion of power and trust was visited on helpless and innocent children in the archdiocese.”

“The perpetrators must continue to be brought to justice, and the people of Ireland must know that this can never happen again,” the government said, also apologizing for the state’s failure to hold church authorities accountable to the law.

The 720-page report — delivered to the government in July but released Thursday after extensive legal vetting — analyzes the cases of 46 priests against whom 320 complaints were filed. The 46 were selected from more than 150 Dublin priests implicated in molesting or raping boys and girls since 1940.

Eleven priests convicted of child abuse are named in the report, but 33 are referred to by aliases and two have their names blacked out because their criminal cases are about to begin in Dublin courts.

The report rejected past bishops’ key claim that they were ignorant of both the scale and criminality of priests’ abuse of children. It documented how the Dublin Archdiocese negotiated a 1987 insurance policy for future legal costs of defending lawsuits and compensation claims.

At the time, bishops knew of at least 17 priests linked to abuse cases, the report said, and “the taking out of insurance was an act proving knowledge of child sexual abuse as a potential major cost to the archdiocese.”

Victims appealed to the government not to let bishops retain the right to decide whether to refer abuse complaints to police.

“Never again should the Catholic Church in Ireland blame others for its own decision to reassign priests (to other parishes) who were clearly a danger to children,” said one abuse victim, Marie Collins. She was raped by a Dublin priest as a 13-year-old hospital patient in 1960, but police and church officials declined to pursue her complaint.

Investigators spent three years poring over 60,000 previously secret Dublin church files. They were handed over by Dublin Archbishop Diarmuid Martin, a veteran Vatican diplomat appointed to Dublin in 2004 with a brief to confront the scandal. Among the files were more than 5,500 that Martin’s predecessor, retired Cardinal Desmond Connell, had tried to keep locked in the archbishop’s private vault.

The investigators, led by a judge and two lawyers, said that while it was not their job to confirm the scale of abuse cases, they had no doubt that the 46 priests abused many more than 320 children.

“One priest admitted to sexually abusing over 100 children, while another accepted that he had abused on a fortnightly basis during the currency of his ministry which lasted for over 25 years,” they wrote.

Three Dublin archbishops — John Charles McQuaid (1940-72), Dermot Ryan (1972-84) and Kevin McNamara (1985-87) — did not tell police about clerical abuse cases, instead opting to avoid public scandals by shuttling offenders from parish to parish and even overseas to U.S. churches, the commission found.

It was not until 1995 that then-Archbishop Connell allowed police to see church files on 17 clerical abuse cases kept in a secret, locked vault, though at the time Connell had records of complaints against at least 29 priests, the report says.

Justice Minister Dermot Ahern said the state would renew efforts to prosecute more of the 46 priests in the report, as well as police officers that the investigation found colluded with church authorities to suppress complaints.

Ahern said, however, that the cover-ups reflected “a different era where there was deference by state agencies to the church. I don’t think that would happen today.”

The investigators lauded a handful of priests and mostly low-ranking police who pursued complaints and prosecutions, almost always unsuccessfully, from the 1960s to the 1980s.

Senior police officers “clearly regarded priests as being outside their remit” and handed “complaints to the archdiocese instead of investigating them,” the report said.

“A few (priests) were courageous and brought complaints to the attention of their superiors. The vast majority simply chose to turn a blind eye,” it said.