Pope Francis begged for forgiveness for the pain suffered by victims of sexual abuse at the hands of Catholic priests and demanded accountability, saying the decades-long abuse and cover ups must be rooted out of the church.

In a letter to Catholics around the world on Monday, Francis blasted the self-referential clerical culture that has been blamed for the crisis, with church leaders seemingly more concerned for their reputations than the safety of children.

“With shame and repentance, we acknowledge as an ecclesial community that we were not where we should have been, that we did not act in a timely manner, realizing the magnitude and the gravity of the damage done to so many lives,” Francis wrote. “We showed no care for the little ones; we abandoned them.”

A Vatican official said it was the first time a pope has written to all of the world’s 1.2 billion Catholics about sexual abuse. Past letters have been addressed to bishops and the faithful in individual counties.

The pope’s 2,000-word letter was issued by the Vatican ahead of Francis’ trip this weekend to Ireland, a once staunchly Roman Catholic country where the church’s credibility has been damaged by its own revelations that priests raped and molested children with impunity and their superiors covered up for them.

Priestly sex abuse was always expected to dominate the trip, but the issue has taken on new gravity following revelations in the U.S. that one of Francis' trusted cardinals, the retired archbishop of Washington, Theodore McCarrick, allegedly sexually abused and harassed minors as well as adult seminarians.

The letter, issued in seven languages and addressed to the “People of God,” also came in response to the new revelations of decades of misconduct by hundreds of Catholic priests in Pennsylvania, where more than 1,000 kids were sexually abused.

A grand jury report last week reported at least 1,000 kids were sexually abused by some 300 “predator priests” over the past 70 years, and that generations of bishops failed repeatedly to take measures to protect their flock or punish the rapists.

"Priests were raping little boys and girls, and the men of God who were responsible for them not only did nothing; they hid it all," the report said.

Francis referenced the Pennsylvania report, saying no effort to beg forgiveness of the victims will ever be sufficient, but vowed “never again.”

He said, looking to the future, "no effort must be spared to create a culture able to prevent such situations from happening, but also to prevent the possibility of their being covered up and perpetuated."

Francis didn't, however, provide any indication of what concrete measures he is prepared to take to sanction those bishops — in the U.S. and beyond — who covered up for sexually abusive priests.

“We have realized that these wounds never disappear and that they require us forcefully to condemn these atrocities and join forces in uprooting this culture of death,” he said.

Unlike the U.S. bishops' conference, which has referred only to "sins and omissions" in their handling of abuse, Francis labeled the misconduct "crimes."

"It is essential that we, as a Church, be able to acknowledge and condemn, with sorrow and shame, the atrocities perpetrated by consecrated persons, clerics, and all those entrusted with the mission of watching over and caring for those most vulnerable," he wrote.

The Catholic Church is also facing sexual abuse scandals in a number of other countries, including Australia and Chile, where Francis strong-armed the 31 active bishops to offer to resign en masse over their handling of abuse. So far he has accepted five of their resignations.

The Associated Press contributed to this report.