The Vatican has insisted there was no cover-up in the church's handling of child sexual abuse.
Reports from The New York Times claimed a US Roman Catholic archbishop warned a top Vatican office led by the future Pope Benedict XVI about a priest who may have molested as many as 200 deaf boys, but the priest never was defrocked.
But the Vatican newspaper L'Osservatore Romano said there was a "clear and despicable intention" to strike at Pope Benedict XVI "at any cost" over the revelations.
The newspaper documents were provided by two lawyers who filed lawsuits alleging the Archdiocese of Milwaukee did not take sufficient action against Father Lawrence Murphy. The priest, who died in 1998, worked at the former St John's School for the Deaf in St Francis from 1950 to 1975.
In 1996, then-Milwaukee Archbishop Rembert G. Weakland sent letters about Fr Murphy to the Vatican office called the Congregation for the Doctrine of the Faith, which was led from 1981 to 2005 by Cardinal Joseph Ratzinger, the future pope.
Eight months later, the second in command at the doctrinal office, Cardinal Tarciscio Bertone - now the Vatican's secretary of state - told the Wisconsin bishops to begin secret disciplinary proceedings, according to the documents. But Cardinal Bertone halted that process after Fr Murphy wrote to Cardinal Ratzinger saying he already had repented, was ailing and that the case's statute of limitations had run out, the Times reported.
Archbishop Weakland also wrote to a different Vatican office in March 1997, saying an attorney's impending lawsuit would make the case public. The documents emerged even as the Vatican deals with an ever-widening church abuse scandal sweeping several European countries.
Benedict last week issued an unprecedented letter to Ireland addressing the 16 years of church cover-up scandals there. But he has yet to say anything about his handling of a case in Germany known to have developed when, as cardinal, he oversaw the Munich Archdiocese from 1977 to 1982.
Meanwhile, four victims of Catholic priest sex abuse have been held by Italian police after demonstrating outside the Vatican. The group of Americans had demanded the pope release all files on paedophile clergy worldwide and sack the guilty.
The four, leaders of the Survivor Network of those Abused by Priests, held up pictures of themselves as children and signs reading "Stop the Secrecy Now". One, Barbara Blaine said they were detained because they did not have a permit for their protest.