Senior Portuguese church officials had previously claimed that only a handful of cases had occurred.

Senior clergymen sat in the front row of the auditorium where panel members read out some of the harrowing accounts of alleged abuse included in their final report. There were vivid and shocking descriptions.

The Independent Committee for the Study of Child Abuse in the Catholic Church, set up by Portuguese bishops just over a year ago, looked into alleged cases from 1950 onward. Portuguese bishops are due to discuss the report at an extraordinary meeting on March 3.

The statute of limitations has expired on most of the alleged cases. Only 25 allegations were passed to prosecutors, the panel said.

The report, criticized by some as long overdue, came four years after Pope Francis gathered church leaders from around the world at the Vatican to address the sex abuse crisis in the church.

That meeting was held more than 30 years after the scandal first erupted in Ireland and Australia and 20 years after it hit the United States.

Bishops and other Catholic superiors in many parts of Europe at the time continued to deny that clergy sex abuse existed or insisted on giving little weight to the problem.

The head of the Portuguese Bishops Conference, Bishop José Ornelas, asked the victims for forgiveness and apologized for the church having failed to grasp the scale of the problem.

Child sex abuse is a “heinous crime,” Ornelas said in a statement he read out later Monday, adding: “It is an open wound which pains and embarrasses us.”

The panel regretted that the Vatican had taken so long to grant access to church archives. Permission came only in October, giving the panel just three months to go through written evidence of abuse.

Pedro Strecht, a psychiatrist who headed the panel in Portugal, said it estimates the true number of victims during the period under study as being at least at 4,815. That extrapolation was made on potential other victims mentioned by those victims who came forward.

The panel is not publishing the names of the victims, the identities of the alleged abusers, or the places the abuses allegedly happened. However, it is to send to bishops by the end of the month a list of alleged abusers who are still active in the church.

The final report includes a separate — and confidential — annex of all the names of church members reported to the committee that is being sent to the Portuguese Bishops Conference and to the police.

The Portuguese church hasn’t said whether it intends to pay compensation to any victims.

The six-person committee included psychiatrists, a former Supreme Court judge and a social worker.

The report said that 77 percent of the abusers were priests, with other perpetrators being linked to church institutions. It added that 77 percent of victims didn’t report the abuse to church officials and only 4 percent went to the police. Most of the abuse took place when the victims were in early adolescence.

It said 48 percent of those who came forward had spoken about the abuse for the first time. Most of the alleged victims were male, though 47 percent were female, the report said.

It said there were places in Portugal, such as some seminaries and religious institutions, that were “real blackspots” for abuse.

Information about child sex abuse found in ecclesiastical records should be regarded as “the tip of the iceberg,” the report said.

Those records frequently do not refer directly to abuse, even when discussing it, and many incidents appear to have been dealt with informally, the panel said.

The panel recommended that the statute of limitations on such crimes be extended to at least 30 years from the current 23 years.