Taking a more critical tone than in the past, Pope Benedict XVI has said that the Roman Catholic Church is embroiled in a sex scandal because of the “sin within” and not because of outside factors.

The Pope, by laying blame on the Catholic clergy, took a different route than many other Catholic leaders who have accused the media of blowing up the situation to crisis proportion.

"The greatest persecution of the Church doesn't come from enemies on the outside but is born from the sin within the Church," the pontiff said to reporters on the papal plane en route to Portugal earlier this week. "The Church needs to profoundly relearn penitence, accept purification, learn forgiveness but also justice."

He said the current global abuse scandal is the greatest threat to the Roman Catholic Church. And while the Catholic Church has always had internal problems, “today we see it in a truly terrifying way,” Pope Benedict said.

To date, the Pope’s remarks are the strongest on the sex abuse scandal that has affected the Catholic Church in Austria, Belgium, Germany, Ireland, Netherlands, and the United States, among other countries. Hundreds of people have reported being abused by priests or other Catholic officials.

Among the many victims worldwide are a group of deaf boys who were molested by a Wisconsin priest. Father Lawrence C Murphy had molested as many as 200 deaf boys at St John’s School for the Deaf in Wisconsin while he worked there from 1950 to 1974. He was never disciplined by the Church’s justice system or tried in government court. Murphy died in 1998 still a priest.

A Gallup Poll in March showed that Pope Benedict XVI’s favourability rating is the lowest since he came to office in 2005. From a favourability rating high of 63 per cent in 2008, the Pope’s rating has fallen to 40 per cent in 2010 amid criticism of the church’s handling of child sex abuse by priests.

In recent weeks, the Pope has accepted the resignations of a few bishops who are either directly involved in sexually abusing children or covering up for priests who did.

The Pope began his four-day visit to Portugal on Tuesday.