Pope Francis said Monday every effort must be made to ensure that the culture of the Catholic Church prevents future clerical sexual abuse of children, and to make sure that if such abuses do take place, they cannot be covered up.
The pope's comments came in a letter to the world's billion-plus Catholics, in response to the latest revelations of abuses by clergy members.
Last week, a U.S. grand jury report said more than 300 predator priests had abused more than 1,000 children in six Pennsylvania dioceses over the span of 70 years.
Never before has Pope Francis written to all Catholics, whom he called "the people of God," on the "crime" of clerical sexual abuse. His letter was issued in seven languages.
"Even though it can be said that most of these cases belong to the past, nonetheless, as time goes on, we have come to know the pain of many of the victims," Francis said in his letter.
He said with "shame and repentance" the Catholic Church acknowledges it did not act in a timely manner and realize the amount of damage the abusers have done to so many people.
Francis said "no effort to beg pardon and to seek to repair the harm done will ever be sufficient."
The letter did not mention any new measures that would be adopted by the church.
Papal spokesman Greg Burke praised the letter. "It is significant that the pope calls abuse a 'crime,' not only a sin, and that he asks for forgiveness; but acknowledges that no effort to repair the damage done will ever be sufficient for victims and survivors," he said.
Pennsylvania Attorney General Josh Shapiro also praised the pope's letter, but urged local church officials to "cease their denials and deflections."
Shapiro called on the Catholic Church to accept all the Pennsylvania grand jury recommendations, which include allowing victims to sue the church for abuse that occurred outside the statute of limitations. The church has long resisted such a measure.
The Catholic Church has long faced cases of sexual abuse by the clergy in many countries. In the past month alone, the pope accepted the resignation of an Australian archbishop convicted in May for covering up child abuse, as well as the resignation of Cardinal Theodore McCarrick, who has also been accused of sexual abuse.
On Monday, the International research group bishopaccountability.org launched a database containing the names of more than 70 Irish clergy convicted or credibly accused of sexually abusing children. Several other countries are facing similar scandals, including Argentina, Australia and Chile.
The pontiff acknowledged in his letter that as a church community, "We did not act in a timely manner, realizing the magnitude and the gravity of the damage done to so many lives. We showed no care for the little ones; we abandoned them."
He said without the participation of all Catholics, the efforts to "uproot the culture of abuse" will fail.
"It is essential that we, as a Church, be able to acknowledge and condemn, with sorrow and shame, the atrocities perpetuated by consecrated persons, clerics, and all those entrusted with the mission of watching over and caring for the most vulnerable," Pope Francis said.