The Bishop of Broken Bay has promised his community that a paedophile priest released from a NSW prison won't be allowed to return to his former parish.

Catholic priest Finian Egan was released from Long Bay Prison on Tuesday morning after serving four years of an eight-year sentence for raping and abusing young girls for nearly three decades.

Coinciding with his release, the Diocese of Broken Bay has begun the process of laicisation, more commonly known as "defrocking", by presenting its case to Rome to have the 83-year-old stripped of his priesthood.

If successful, Egan will no longer be regarded as a priest and the church will no longer be responsible for him.

"These processes can be complex given that the one Roman office deals with all requests that are submitted from all over the world," the Bishop of Broken Bay the Most Reverend Peter Comensoli explained in a statement on Tuesday.

While Egan has the right to argue his case, the bishop has already used his power to immediately dismiss him from the public ministry.

On Monday, the bishop shared the other additional conditions placed on Egan, in an online letter to reassure the people of his parish.

"This development will occasion different reactions and emotions for many of you, even distress, especially for those who may have known Finian, and most particularly for those who have been offended against and hurt by him," he wrote.

The elderly priest is never to exercise any priestly ministry; refer to himself as a priest; seek accommodation in places where he had previously been a priest; or present to any person or parish site in the Diocese of Broken Bay, according to the bishop's letter.

"My restrictions will be clearly articulated to Finian with the expectation that he will comply during this time," he wrote - adding later that breaking the restrictions would be reported to Rome as part of the dismissal process.

Egan was found guilty of rape and seven counts of indecent assault by a jury in 2013. He was sentenced to eight years in jail with a non-parole period of four years.

The bishop revealed on Tuesday the church had further concerns saying "the matters for which Finian Egan has been convicted do not exhaust the number of complaints that have been received in his regard".

The bishop says police were informed in all matters brought to the church's attention.

The diocese defended its decision to wait four years from Egan being found guilty before initiating the proceedings, saying it was a "complex" process.

The child abuse royal commission's final report, handed down on Friday, criticised the Vatican for being slow to respond to petitions from Catholic Church authorities in Australia to dismiss those found to have committed child sexual abuse.

It also recommended celibacy should be voluntary for the clergy to reduce the risk of harm to children.