One such case involves Bishop Carlos Sevilla of Yakima, Wash., who is accused of hiding incidences of sexual misconduct involving priests and other church workers, The Washington Post reported Saturday.

"Action has been taken against some priests, but action hasn't been taken against U.S. bishops," said Terry McKiernan, president of BishopAccountablity.org.

Incidents Sevilla is accused of covering up include a priest convicted of fondling a 14-year-old girl and a man accused of watching child pornography.

On his recent visit to the United States, Pope Benedict XVI said sex scandals linked to the church have on some occasions been ineffectively handled and it is the bishops' "God-given responsibility" to rebuild lost trust.

Since his visit, Catholic activists have urged the pope to do something about bishops who may have hesitated in stopping sexual abuse.