The Catholic Archbishop of Sydney, Anthony Fisher, has told Australia's Royal Commission into institutional child sex abuse that the response by Catholic Church to allegations amount to 'criminal negligence'.

Fisher, aged 57, who succeeded Cardinal George Pell as Archbishop of Sydney in 2014, said: 'It was a kind of criminal negligence to deal with some of the problems that were staring us in the face.

'In other cases, I think there were people that were just like rabbits in the headlights, they just had no idea what to do, and their performance was appalling,' he added according to ABC.

Archbishop of Perth Timothy Costelloe admitted there had been a 'catastrophic' failure in Church leadership.

He said child sex abuse ran counter to what the Church claimed to be.

He said: 'That leads me to reflect there has also been a catastrophic failure in keeping people faithful [like priests] to the commitments they made. I asked myself what can possibly have gone wrong, or what was missing, that could lead to, not just one, but countless people failing in this way.'

They were among five Catholic archbishops currently giving evidence to the commission, which has been running for four years. They were asked how they had addressed the failures in leadership and responded that they were taking a more collaborative approach.

The archbishops were grilled about what they had done to deal with those 'catastrophic failures' in leadership they had agreed were at the root of the child sexual abuse.

Costelloe said that the problem had the potential to return if it was not dealt with effectively. In the past, he admitted, the Vatican had believed itself utouchable because it was 'so unique and so important'.