The Roman Catholic Church in the Australian state of Victoria has confirmed that more than 600 children have been sexually abused by its priests since the 1930s.
The Archbishop of Melbourne, Denis Hart, described the figures as "horrific and shameful".
They were released in a submission to a state parliamentary inquiry into the handling of abuse cases.
Campaigners say the true number of abuse victims could be up to 10,000.
In its submission, the church said the 620 cases went back 80 years with the majority taking place between the 1960s and the 1980s.
It says it is still investigating a further 45 cases.
In a statement, Archbishop Hart said it was important to be open "about the horrific abuse that has occurred in Victoria and elsewhere".
"We look to this inquiry to assist the healing of those who have been abused, to examine the broad context of the church's response, especially over the last 16 years, and to make recommendations to enhance the care for victims and preventative measures that are now in place," the statement said.
Campaign groups say that many cases of abuse have gone unreported, and they believe the true number of victims is closer to 10,000 in Victoria alone.
Abuse of children by Roman Catholic priests has been a major issue in Australia recent years.
During a visit to Australia in July 2008, Pope Benedict XVI met some of the victims and made a public apology for the abuse.