The Vatican has expressed "shame and sorrow" over revelations that Catholic priests in Pennsylvania sexually abused about 1,000 children over seven decades.

It comes as US bishops vowed to involve non-clerical experts in abuse investigations.

The Vatican vowed to hold accountable sexually abusive priests and bishops who enable them to continue to prey on minors.

Vatican spokesman Greg Burke said church officials needed to comply with all laws about reporting suspected abuse to authorities.

On Tuesday, Pennsylvania released a report that followed a two-year investigation into sexual abuse by some 301 clergymen dating back 70 years.

It contained graphic examples of children being groomed and sexually abused by priests.

US bishops have called on the Vatican to investigate accusations of sexual abuse against former Washington, DC Cardinal Theodore McCarrick. The Vatican did not directly address their request.

Pope Francis accepted the former cardinal’s resignation in July after American Church officials said allegations that he sexually abused a 16-year-old boy almost 50 years ago were credible and substantiated.

He was the first cardinal in living memory to lose his red hat and title.

Pope's record on child protection a 'dismal failure'

"The overarching goal in all of this is stronger protections against predators in the church and anyone who would conceal them, protections that will hold bishops to the highest standards of transparency and accountability," said Cardinal Daniel DiNardo, president of the US Conference of Catholic Bishops.

The bishops said they would create a new way to report accusations of sexual abuse by clergy members and for claims to be investigated without interference from bishops overseeing priests accused of sex abuse.

They said it would involve more church members who were not clergy but had expertise in law enforcement or psychology.

Nick Ingala, a spokesman for Voice of the Faithful, a group formed to promote parishioners' voices after the abuse scandal surfaced, said it was heartening that bishops wanted to set up an independent review process but he expressed skepticism that it would be successful.

"I don't know how they are going to work that out," he said in a telephone interview.

"I'm always hesitant to give 100% credence to any plan the bishops put forth based upon experiences in the past."