Under the territory's expanded reportable conduct scheme, priests in Canberra will be required to report allegations, offences or convictions related to children to the ACT Ombudsman within 30 days from March 31, 2019 - even if the information was gleaned in the confessional.

But the Australian Catholics Bishops Conference wrote to ACT Chief Minister Andrew Barr to say mandatory reporting from the confessional "will either have no effect on child safety or will actually make children less safe"

The letter, signed by Brisbane Archbishop Mark Coleridge and Sydney Archbishop Anthony Fisher, also said the laws impinged on the human right to freedom of religion.

"Freedoms of conscience, thought, speech, assembly, religious belief and practice are basic human rights, one recognised in international law, to some extent in Australian domestic law and more broadly in Australian culture," the letter says.

"The human rights to freedom of conscience, religious belief and practice include the right of believers to engage in rituals such as confession without fear of being bugged by others (even the civil authorities).

"Not to recognise confessional privilege would go against these long standing philosophical legal and cultural commitments and well recognised norms, the force a priest to breach the seal would be to force him to act against fundamental tenets of his faith.

"Put badly without the seal of confession, the sacrament as understood by Catholic and Orthodox Christians would be impossible."

But Dr Helen Watchirs from the ACT's Human Rights Commission said human rights laws does not require blanket protection to be afforded to the seal of the confessional.

"In our view, the benefit to the community of maintaining the confidentiality of the confessional should not outweigh the potential danger to children of withholding information," Dr Watchirs said.

"Given the centrality of the confessional in particular religious traditions, extending mandatory reporting laws to cover information received during the rite of confession clearly involves serious limitations on the right to freedom of conscience, religion and belief, and must be properly justified in accordance with the Human Rights Act."

Dr Watchirs said limitations on rights had to "meet a legitimate objective, and be a rational and proportionate response" to that objective in order to comply with the ACT's human rights laws.

"There is no question that the protection of children from sexual abuse is a fundamentally important objective, which is consistent with the protection of children’s rights in the Human Rights Act," she said.

"But for compliance with the Human Rights Act, it is also important to be satisfied that the removal of the exemption/privilege will assist to achieve the objective of exposing offenders and protecting children.

"The Royal Commission, having considered all the evidence, was satisfied that religious confession remains a forum in which abuse may be disclosed."

Under church law, priests can be ex-communicated for breaking the seal of confession.

The Royal Commission into Institutional Responses into Child Sexual Abuse heard evidence of abuse disclosed in the confessional - both from victims and abusers themselves -  and recommended mandatory reporting laws be extended to cover this.

However former Catholic priest Paul Collins told ABC Radio Canberra on Thursday abusers would go nowhere near the confessional if there was mandatory reporting.

“I have to say, having commented on this many many times I have to say from both points of view, both from the letter of Archbishop Coleridge and Archbishop Fisher and the response of the ACT government we’re dealing with a beat up," Dr Collins said.

"The simple reality in the Catholic Church, although the caricature is that Cathol

ics run off to confession every minute of the day, in fact the vast vast majority of Catholics have never been near the confessional for the years.

"I personally think, and it’s just a personal view, the royal commission in a way exaggerated the importance of the confessional and what I think it does is it gives governments an excuse to look like they’re actually doing something."

The South Australian government has also expanded its mandatory reporting laws, with priests legally obliged to report any confessions of child abuse from October 1, or face a $10,000 fine.

The NSW and Victorian governments are yet to decide if they will follow suit.

An earlier version of this story incorrectly said Archbishop Mark Coleridge was from Melbourne.