The head of Australia’s royal commission into child sex abuse has condemned Catholic church leaders for failing to recognise the sexual assault of children as a crime.

Speaking publicly about the royal commission for the first time, Justice Peter McClellan said on Tuesday that commissioners had heard from many leaders of the Catholic church, some of whom argued sexual abuse was a “moral failure” rather than a criminal act.

Commissioner seeks to guarantee compensation: Justice Peter McClellan. Credit:Jeremy Piper

“I cannot comprehend how any person, much less one with qualifications in theology ... could consider the rape of a child to be a moral failure but not a crime,” Justice McClellan said in a speech to the Australian Human Rights Commission. “This statement by leaders of the Catholic Church marks out the corruption within the Church both within Australia, and it seems from reports, in many other parts of the world.”

Rather than ensuring that offenders were subject to the criminal law, ineffectual attempts at "treatment" of offenders was undertaken by the church, he said.