Australia's most senior Catholic says the royal commission will help determine whether reports about child abuse in the church have been a "significant exaggeration".
"We think it's an opportunity to help the victims. It's an opportunity to clear the air, to separate fact from fiction," Cardinal George Pell told reporters in Sydney.
He said the church had been worked hard to uncover child abuse.
VIDEO: Highlights of this afternoon's press conference
"We are not interested in denying the extent of misdoing in the Catholic Church. We object to it being exaggerated," Cardinal Pell said.
"We object to being described as the only cab on the rank.
"We acknowledge, with shame, the extent of the problem and I want to assure you that we have been serious in attempting to eradicate it and deal with it ...
"This commission will enable those claims to be validated or found to be a significant exaggeration."
Cardinal Pell also questioned whether ongoing "furore in the press" about the alleged abuse was helpful to the victims.