A survivor of clerical abuse says "every rotten apple" should be gotten rid of from the Catholic church.

Marie Collins was speaking at The World Meeting of Families in Dublin's RDS.

The gathering heard there is denial within the Catholic church about the scale of clerical sex abuse.

Ahead of the arrival of Pope Francis on Saturday, there are calls for the Vatican to come up with a plan to address the issue.

Ms Collins was abused by a priest as a child - she says survivors want more than just an apology from the Pontiff.

"Sadly still in the church, among clergy and laity, there are people who prefer to believe that all this is media conspiracy - just survivors trying to destroy the church - and they deny and defend.

"I hope that they will take their energies from defending the indefensible, accept the truth and instead of denial put their energy into bringing changes that are needed."

Marie Collins at a session called Safeguarding Children and Vulnerable Adults during the World Meeting of Families in the RDS, Dublin | Image: Leah Farrell/RollingNews.ie

She wants a zero-tolerance approach to those found to be perpetrating or covering up abuse.

"I think there is this fear of the domino effect: that if you start looking at bishops and they start being removed, how many more is it going to (take) down the line?

"I think it shouldn't matter: every one, every rotten apple should be got rid of - and it should happen now".

Ms Collins resigned from the Vatican’s Commission for the Protection of Minors last year, having been a member of the commission since its inception in 2014.

She cited her "frustration at the lack of cooperation with the commission by other offices in the Roman Curia".

But she also accepted an invitation from Cardinal Seán Patrick O’Malley to continue to work with the commission in an educational role.

Additional reporting: Jack Quann