MPs said the royal commission into sexual abuse should examine the issue and recommend that, where necessary, state criminal codes be harmonised to mandate that priests go to the police in child sexual abuse matters.

The federal Attorney-General, Nicola Roxon, who is charged with setting up the commission, agreed the seal of Confession should be looked at, but she cautioned against too much focus on the issue.

Ms Roxon said the commission's remit would be much broader than just the Catholic Church.

And while the church ''will be a key part of this'', the issue of confessions not being referred to the police was not a major factor in the church when it came to covering up or failing to report child sexual abuse.

''While it's a difficult and prominent religious issue, it's not the core of what's being looked at,'' she said.

Ms Roxon said there were ''much more blatant and open failures'' to stop abuse that needed to be examined and not just in the church, but other institutions as well. These included turning a blind eye to abuse, not acting on complaints by victims and not acting on ''open secrets'' that a certain individuals within organisations were child abusers.

The federal government, which has begun consultations with the states, churches and other interested parties on the terms of reference, is aiming to have the details finalised at a premiers conference in Canberra on December 7.

Fairfax Media understands that key states, including NSW, will be asked to jointly appoint the commissioner to effectively establish a federal-state royal commission, giving it maximum powers to compel all organisations to appear and testify, be they state or federal. The issue of Catholic confessions reared when Cardinal George Pell said the seal of Confession was inviolate.

The Premier, Barry O'Farrell, questioned the convention but said his government had no plans at this stage to change NSW law.

The Prime Minister said all adults had ''a duty of care towards children and it is not good enough to engage in sins of omission and not act when a child is at risk''.

The NSW policeman Peter Fox, who blew the whistle last week on alleged abuses and cover-ups by the Catholic Church in the Hunter Valley, leading to the royal commission, favoured mandating priests to break the seal of Confession.

''How many Hail Marys are priests to say after confession to be forgiven for raping an eight-year-old child then have a clean slate to start again?'' he tweeted.

For help go to www.sexualassault.nsw.gov.au.