Washington • The Justice Department has launched an investigation into alleged sexual abuse of youths by Catholic clergy across Pennsylvania, according to people familiar with the matter.

The move by the Justice Department to launch such a probe, even one limited to a single state, marks a major escalation in the government’s response to allegations that the church spent decades hiding the extent of the sexual abuse problem among its priests, and allowing pedophiles to continue to work and live undetected in communities.

“This is just a breathtaking, stunning and very welcome development,” said Michael Dolce, a lawyer who represents victims of sexual abuse.

The U.S. attorney’s office in Philadelphia began issuing subpoenas recently, according to one person familiar with the matter. A spokeswoman for the U.S. attorney, William McSwain, declined to comment, though church officials around the state confirmed having received subpoenas.

The subpoenas seek years of internal church records, including any evidence of church personnel taking children across state lines for purposes of sexual abuse, any evidence of personnel sending sexual material about children electronically and any evidence church officials reassigned suspected predators or used church resources to try to further or conceal such conduct, according to a person familiar with the matter.

The investigation was sparked after a state grand jury issued a scathing report in August finding that more than 300 Catholic priests in Pennsylvania had sexually abused children over seven decades, protected by a hierarchy of church leaders who covered it up.

The lengthy report identified about 1,000 children who were victims but concluded there were probably thousands more.

“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. For decades,” the grand jury wrote in its report.

The report was the product of an 18-month investigation into six of the state’s dioceses — Allentown, Erie, Greensburg, Harrisburg, Pittsburgh and Scranton — and follows other state grand jury reports that revealed abuse and cover-ups in two other dioceses.

The federal investigation was first reported by The Associated Press.

Dolce said federal laws involving conspiracy and sex crimes across state lines could give investigators legal tools to investigate conduct that reached back over decades.

The decision to launch the investigation was made by federal prosecutors in Philadelphia, not senior Justice Department officials in Washington, according to the person familiar with the matter.

Since the Catholic clergy’s sexual abuse scandal became a nationwide story in 2002, the Justice Department has largely stayed away, leaving the issue to local prosecutors to pursue whatever cases they could under their states’ statutes of limitations. The church has also struck a series of financial settlements with those who have pursued lawsuits seeking damages.

In Allentown, the diocese said in a statement it “will cooperate fully with the request, just as it cooperated fully with the information requests related to the statewide grand jury. The Diocese sees itself as a partner with law enforcement in its goal to eliminate the abuse of minors wherever it may occur in society.”

The move from the Justice Department comes as the Pennsylvania General Assembly has balked at taking action on the issue of clergy abuse in the state.

The grand jury that released its report in August made recommendations for legislators, including extending the criminal statute of limitations for sexual abuse of children and opening a two-year window for victims to sue their abusers. Under current state law, the Pennsylvania attorney general’s office was only able to charge two of the 301 priests named in the report; the second pleaded guilty this week.

The state House passed a bill that would have enacted the grand jury’s recommendations, but on the final day scheduled for voting on Wednesday, the Senate did not pass the bill.

The state attorney general’s office has strongly urged the Senate to pass a bill.

“We’re fighting the fight in the Pennsylvania legislature. That led to a standstill last night, but it’s not over,” attorney general’s office spokesman Joe Grace said on Thursday. He urged Senate leaders to call legislators back to Harrisburg for another day of voting. “The attorney general made clear that we’re not going away. Neither are the victims.”

Pennsylvania is believed to have conducted more investigations of institutional child sex abuse than any other state, but there is no full accounting of abuse in the Catholic Church in the United States.

Peter Isely, a longtime advocate for victims of sexual abuse, said groups have long been pressing the U.S. government for a national investigation of child sex abuse, especially in the Catholic Church. Isely, who was abused and is a spokesman for the global group Ending Clergy Abuse, said that a five-year inquiry in Australia is “the gold standard,” but that other nations, including Canada, Germany and Ireland, have conducted national forensic reviews.

“Imagine if they did what was done in Pennsylvania, but nationwide,” he said, arguing that the problem needs to be solved by the Vatican.

In America, the most far-reaching study was one conducted in 2004 by the John Jay College of Criminal Justice at the City University of New York. It reviewed abuse by priests and deacons from 1950 until 2002.

Worldwide, national law enforcement agencies are targeting abuse within the church. In Chile, prosecutors and police this summer raided church offices, confiscating documents and looking for evidence of crimes that went unreported to police.