HARRISBURG, Pa. (Reuters) - Roman Catholic priests in Pennsylvania sexually abused thousands of children over a 70-year period and silenced victims through “the weaponization of faith” and a systematic cover-up campaign by their bishops, the state attorney general said on Tuesday.

An 884-page report made public by Pennsylvania Attorney General Josh Shapiro after a two-year investigation contained graphic examples of children being groomed and sexually abused by clergymen. It was largely based on documents from secret archives kept by the dioceses, including handwritten confessions by priests, he said.

“It was child sexual abuse, including rape, committed by grown men - priests - against children,” Shapiro told a press conference.

Representatives of the six Pennsylvania dioceses included in the report could not be reached for comment.

The attorney general said it was the most comprehensive report on Catholic clergy sex abuse in American history, nearly two decades after an expose of widespread abuse and cover-up in Boston that rocked the Roman Catholic church.

Several of the dioceses issued statements apologizing to victims and saying they were taking steps to ensure any criminal behavior was stopped. “The grand jury has challenged us as a Catholic diocese to put victims first and to continue to improve ways to protect children and youth,” Bishop Lawrence Persico of the Erie Diocese said in a statement.

As accusers wept behind him, Shapiro described alleged abuse by priests in six of the state’s eight dioceses, including a group of Pittsburgh clergymen accused of ordering an altar boy to strip naked and pose as Christ on the cross while they photographed him.

“The pattern was abuse, deny and cover up,” Shapiro said, adding that church officials sought to keep abuse allegations quiet long enough so they could no longer be prosecuted under Pennsylvania’s statute of limitations.

“Priests were raping little boys and girls,” Shapiro said. “They hid it all for decades.”

Storm clouds pass over a Roman Catholic church in Pittsburgh, Pennsylvania, U.S. August 14, 2018. REUTERS/Jason Cohn

The report cited 301 priests, some of whom have died. Only two of the priests are still subject to prosecution.

A few of the clergymen accused in the report succeeded in having their names redacted, and Shapiro said he would argue at a Sept. 26 court hearing for making all the names public.

He said the grand jury identified about a thousand victims, but believed there may be many more.

Shapiro said that one priest had molested five sisters in one family, he said. The diocese settled with the family after requiring a confidentiality agreement, he said.

The attorney general said that Catholic bishops covered up child sexual abuse by priests and reassigned them repeatedly to different parishes. “They allowed priests to remain active for as long as 40 years,” he said.

Describing the “weaponization of faith” to silence victims, Shapiro cited several examples including one priest who allegedly told children “how Mary had to lick Jesus clean after he was born” to groom them for oral sex.

“Children were taught that this abuse was not only normal but that it was holy,” Shapiro said.

Since the Boston abuse scandal erupted in the 1990s, accusations involving American clerics have sporadically surfaced.

Theodore McCarrick, a former archbishop of Washington, resigned as a cardinal last month after accusations resurfaced that he abused a 16-year-old boy decades ago.

In recent months, Pope Francis accepted a number of resignations from Chilean bishops in a sex abuse scandal that has rocked that country.