It follows a state grand jury report that found at least 1,000 children had been abused by over 300 “predator priests” in six dioceses over 70 years.
The August report came after an 18-month-long investigation into the dioceses in Pennsylvania.
The US attorney in Philadelphia has begun issuing subpoenas.
Federal prosecutors are now investigating whether priests or other clergymen committed federal crimes, the Associated Press reports, citing two people familiar with the inquiry.
US Attorney William McSwain has requested documents from secret archives, confidential files and historical records, including finances, insurance coverage and clergy assignments, according to the Associated Press.
A number of dioceses in Pennsylvania confirmed they had received subpoenas with Allentown, Erie, Harrisburg, Philadelphia, Pittsburgh and Scranton saying they would co-operate with the inquiry.
Pennsylvania is home to over three million Catholics.
The state is believed to have the highest number of grand jury investigations into child sex abuse in the church nationwide, according to US media.
Following the 14 August grand jury report, Pope Francis condemned the “atrocities” of child sex abuse and clerical cover-ups.
Only two priests were charged as a result of the investigation as most of the cases were too old for prosecution.
In a letter to all Roman Catholics, he called for an end to the “culture of death” in the Church.
What was in the report?
The Pennsylvania grand jury, which convened in 2016, interviewed dozens of witnesses and examined more than 500,000 pages of internal documents from six dioceses.
Their report states that young boys and girls, as well as teenagers, were abused by clergy, and that those incidents were systemically covered up by the church.
Many victims claimed they were drugged or otherwise manipulated. Some recalled being beaten by family members who did not believe their stories.
The report also criticised Washington DC Archbishop Cardinal Donald Wuerl, formerly of the Pittsburgh diocese, for his role in concealing the abuse. Cardinal Wuerl was not accused of sexual abuse himself.
Earlier this month Cardinal Wuerl announced his resignation as Washington’s archbishop so that the church could “focus on healing and future”.
