Children at more than 1,000 Catholic institutions across Australia have reported sexual abuse, an inquiry has heard.
The Royal Commission into Institutional Responses to Child Sexual abuse began its investigation into the Catholic Church and other institutions in 2013.
Commissioners surveyed Catholic Church authorities and found that between 1980 and 2015, 4,444 people reported they had been abused at Catholic institutions according to Gail Furness, the lead lawyer assisting the commission.
The average age of the victims was 10.5 for girls and 11.5 for boys.
Francis Sullivan, chief executive of the Truth Justice and Healing Council which is co-ordinating the Catholic Church's response to the inquiry, said the data reflected "a massive failure" by the Church to protect children.
"These numbers are shocking, they are tragic and they are indefensible," he told the commission.
"As Catholics, we hang our heads in shame."
A number of senior Australian Catholics will be testifying over the next few weeks.
The commission's final report is due by the end of this year.