The Vatican said that 76-year-old Justin Rigali, formerly the cardinal-archbishop of Philadelphia, was stepping down because of his age.

But his diocese faces criminal charges for allegedly covering up for paedophile priests by sending them to new parishes.

A Philadelphia grand jury said earlier this year that Mr Rigali had "kept many priests in the area in active ministry despite credible allegations of sexual abuse."

The jury also said the church hushed-up accusations and hadn't told the police. Church officials called their report "a vile, mean-spirited diatribe."

Mr Rigali is expected to be replaced by Archbishop Charles Chaput of Denver, who opposes government health care, gay marriage and stem-cell research.

He caused a stir in 2010 by backing a Catholic school which refused to enrol children raised by gay or lesbian couples.