Bishop Gino Reali of Porto San Rufina outside Rome is charged with complicity in the abuse crimes of Ruggero Conti, who was arrested in June 2008 and is being tried on charges of sexually abusing children in his parish.
Reali "should have told Italian judicial authorities" as well as the Congregation for the Doctrine of the Faith — the Vatican body that deals with sex abuse allegations — about the case, lawyer Farbrizio Gallo told AFP.
Testifying at Conti's trial earlier this month, Reali said he initially did not believe the rumours about Conti but set up a diocesan tribunal after two self-declared victims stepped forward.
But he threw out the case after one of the two did not show up at a hearing of the diocesan tribunal, Reali said.
Gallo said he and the victim decided to press charges after Angelo Bagnasco, head of the Italian Bishops' Conference, last week acknowledged the "possibility" that bishops had covered up paedophile priest cases.
The Roman Catholic Church has since late last year been embroiled in a series of sex abuse scandals amid allegations that the Vatican had shielded predator priests from prosecution in several European countries and the United States.
Italy seemed unconcerned by the revelations, but cases have been coming under the national spotlight in recent weeks.
On Tuesday, a top bishop gave a first official figure on cases in Italy, saying the Church had carried out some 100 canonical investigations of priests suspected of abuse in the country over the past 10 years.
The bishops' conference did not say how many priests were found guilty.
A 73-year-old priest in northern Italy was arrested last week over allegations that he sexually abused a boy for four years from when he was 13.
SIC: MG