Australia's Catholic bishops have written to the prime minister opposing laws requiring priests to break the seal of confession to reveal child sexual abuse.
Catholic priests in Tasmania will report child sexual abuse to police but not if it has been revealed during confession.
Australia's Catholic bishops are rejecting moves to force priests to break the seal of confession to reveal child abuse, with the South Australian church declaring its priests will defy new mandatory reporting laws in that state.
The Tasmanian government also plans to extend mandatory reporting to include information disclosed in a religious confession.
The Catholic Archbishop of Hobart Julian Porteous backs mandatory reporting but not when it means breaking church law that requires priests to uphold the seal of confession.
He says any allegations and suspicions of child or vulnerable adult abuse must be reported and acted on.
"The Catholic Church in Tasmania has zero tolerance for the abuse or neglect of children or vulnerable adults and is committed to acting in their best interests," he said on Wednesday.
He joined Catholic bishops across Australia in opposing any legal changes forcing the reporting of abuse revealed in confession, which under canon law would result in a priest's excommunication from the church.
The Australian Catholic Bishops Conference has told Prime Minister Malcolm Turnbull making the practice of one of the Christian sacraments illegal would make no child safer, partly because "perpetrators of this terrible sin very rarely seek out confession".
"Paradoxically, while those seeking to remove confessional privilege hope thereby to make children safer, the net effect will be to make children less safe," the ACBC letter said.
"By removing the seal, we lose the rare opportunity to point an offender or victim in the direction of the authorities and other assistance."
Tasmanian law already requires any adult to report abuse or neglect but the government says the act is silent on the issue of requiring people in religious ministry to report information revealed in confession to child protection authorities.
Responding to the child abuse royal commission's final report, the government said it had agreed in-principle that mandatory reporting include priests and information disclosed in religious confessions.
"That does lift the veil on the confessional," Attorney-General Elise Archer told reporters.
She said it was a matter for the Catholic Church nationally to consider.
"I realise that that has implications for centuries-old canon law."
Ms Archer said the government also planned to create a criminal offence for failing to report child sexual abuse, although the details needed further consideration.
Catholic priests in Tasmania have received training in mandatory reporting as part of a Hobart archdiocese program that requires abuse be reported to external authorities and the archbishop's office.