Secret Vatican guidelines for priests who father children have been revealed thanks to the efforts of a campaigning son of a cleric, the New York Times reveals.

Irishman Vincent Doyle was 28 when he discovered that the Roman Catholic priest he had known as his godfather was in truth his biological father.

The revelation led him to set up Coping International, a support group for other children of priests, which he says has 50,000 users in 175 countries. 

In October 2017, an archbishop showed Doyle a Vatican document outlining the guidance for priests, who take a vow of celibacy.

“I can confirm that these guidelines exist,” Vatican spokesman Alessandro Gisotti wrote in response to a query from The New York Times. “It is an internal document.”

Gisotti told the newspaper that the 2017 text gathered together a decade’s worth of procedures and that its “fundamental principle” was the “protection of the child.”

He said the guideline “requests” that the father leave the priesthood to “assume his responsibilities as a parent by devoting himself exclusively to the child.”

But religious lawyers say that there is nothing in church law that forces priests to leave the priesthood for fathering children.

According to the Catholic Bishops of Canada, such matters are handled on “an individual diocesan basis.” 

“The position of the Bishops of Canada is clear: any complaint concerning the improper conduct of a Catholic priest must be referred to his diocesan bishop,” the bishops said in a statement to Coping International.

“All such matters are important and should be directed to the bishops concerned immediately. All bishops are very concerned about any misconduct, and I urge you never to hesitate to contact the bishop concerned.”

Catholic religious orders from around the world apologized Tuesday for having failed to respond when their priests raped children, acknowledging that their family-like communities blinded them to sexual abuse and led to misplaced loyalties, denial and coverups.

The two umbrella organizations representing the world's religious orders issued a joint statement ahead of Pope Francis' sex abuse prevention summit, which opens Thursday.

They vowed to implement accountability measures to ensure that coverups by religious superiors end and that children are always safe in the presence of clergy.

Doyle is scheduled to meet privately in Rome with several prominent members of the church hierarchy.

--- With files from The Canadian Press