Lisbon: At least 4,815 children were sexually abused by members of the Portuguese Catholic Church - mostly priests - over the past 70 years, a report by the commission investigating the issue said on Monday, adding the findings are the tip of the iceberg.

"(We want) to pay a sincere tribute to those who were abuse victims during their childhood and dared to give a voice to silence," said child psychiatrist Pedro Strecht, who headed the commission. "They are much more than a statistic."

Strecht said the 4,815 cases were the "absolute minimum" number of victims of sexual abuse by clergy members in Portugal since 1950.

Most perpetrators (77 per cent) were priests and most of the victims were men, Strecht said, adding that they were abused in Catholic schools, churches, priests' homes, and confessionals, among other locations.

The majority of the sexual abuses took place when the children were aged 10-14, with the youngest victim being just two-years-old.

Jose Ornelas, head of the Bishops' Conference, attended the final report's presentation and will respond to it later on Monday. The Church has previously said it was prepared to "take appropriate measures".

Hans Zoller, the Vatican official responsible for child sexual abuse cases, also attended the event in Lisbon. He said it was important to "continue to listen to victims because this will not be the end of it".

"There will be more victims who will come forward," he said, adding it was now the responsibility of the Bishops' Conference to inform the Vatican about the report. "We (Church) need to...(look) into the past."

The Portuguese Catholic Church was rocked last year by cases of an alleged cover-up of sexual abuse including by bishops who remain active in church roles. The commission said it was preparing a list of accused priests still working.

The Portuguese commission started its work in January 2022 after a report in France revealed around 3,000 priests and religious officials sexually abused over 200,000 children.

The abuse allegations have come from people from various backgrounds, from every region of the country and also from Portuguese nationals living in other countries in Europe, Africa and the Americas.

The commission spoke with over 500 victims, analysed historical church documents and interviewed bishops and other clergy members.

A total of 25 of the testimonies heard by the commission were sent to the public prosecutor's office for investigation as all others were committed over 20 years ago and legal proceedings can no longer be initiated.

The commission said the law should be changed so legal proceedings can be initiated for historic crimes committed 30 years ago.

The commission, which says it is independent, was financed by the Catholic Church. Asked by Reuters in December 2021 if that could be a threat to the commission's independence, Strecht said he would be the first to walk out and denounce it if the church intervened in the process.