The clerical abuse scandal represents the greatest threat to the Roman Catholic Church and the crisis was "born from sins within the church" not outside, Pope Benedict XVI said Tuesday on a trip to Portugal.
He called for profound purification and penance within the church as well as pardon and justice.
In some of his strongest comments to date, Benedict said the Catholic church had always suffered from internal problems but that "today we see it in a truly terrifying way."
"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. "The church needs to profoundly relearn penitence, accept purification, learn forgiveness but also justice."
Benedict was responding to journalists' questions, submitted in advance, aboard the papal plane while en route to Portugal, where he began a four-day visit Tuesday.
His comments appeared to repudiate the Vatican's initial response to the scandal, in which it blamed the media as well as pro-choice and pro-gay marriage advocates for mounting a campaign against the church and the pope in particular.
Since then, however, Benedict has called for penance and promised the church would take action to protect children and make abusive priests face justice.
As far as the church's purification is concerned, Benedict has already been cleaning house, accepting the resignations of a few bishops in recent weeks who either admitted they sexually abused youngsters or covered up for priests who did.
Just last week, the pope took control of the conservative Legionaries of Christ order after it was discredited by revelations that its founder fathered at least one child and sexually abused young seminarians.
More bishop resignations have been tendered and the Vatican official in charge of handling sex abuse cases has said he would not be surprised if the pope asks for more.
While the abuse scandal greatly overshadowed the pope's press conference, Portugal has not experienced the wave of priest abuse claims that have emerged in other European countries, including the pontiff's native Germany, as well as Austria, Belgium and Ireland among others.
Portugal, however, is undergoing the same problems that other European nations are experiencing in terms of a financial crisis.
Portugal's economic growth has been pedestrian for years, averaging less than 1 percent between 2001-2008, and the global downturn brought a steep contraction of 2.7 percent last year. A three-year austerity plan to ease the country's crippling debt load is expected to bring greater hardship to a people already feeling the pinch.
The pope said the fiscal crisis demonstrated the need for "moral responsibility" in the economics sphere and noted that he outlined his vision for a more ethical financial system in his 2009 encyclical "Charity in Truth."
Associated Press Writer Barry Hatton in Lisbon contributed to this report.