The Vatican's top diplomat accused the media of "shameful and mystifying" coverage of allegations of sexual abuse by Italian priests and suggested there might be a campaign against the Church.

Vatican Secretary of State Tarcisio Bertone took aim at reporting of a probe by Turin prosecutors into clergy accused of paying a 24-year-old man to keep quiet about past abuse.

A separate investigation involves accusations of abuse by one of Italy's best-known priests, 82-year-old Pietro Gelmini.

In comments to Vatican radio published on Tuesday, Bertone said he respected the work of the prosecutors but criticised the media for paying so much attention to unproven accusations that he said warped the image of the Roman Catholic Church.

Giving too much attention to such accusations was "a false way to present the Church, as if you presented a dark fragment of the great Sistine Chapel ... which (after restoration) has reacquired Michelangelo's original colours," he said.

"Sometimes it seems like there is a plan (to the coverage)."

The Italian Church has not suffered sexual abuse scandals like those in the United States, where the Archdiocese of Los Angeles reached a record $660 million settlement last month with victims of sexual abuse.

However, Italian media have recently given prominence to questions about possible abuse by clergy, and state broadcaster RAI aired in May a BBC documentary about paedophilia by priests.

Bertone criticised the focus on a prestigious Turin school where one of the accused priests worked and which counts Bertone among its former pupils.

"For a week, in newspapers or on TV news, to always see the outside of this institute is truly shameful and mystifying. It's absolutely something to condemn," he said.

La Stampa newspaper, which has led coverage of the investigations, defended its work.

"La Stampa has put out news that has been shown to be true, and ... given it prominence," said La Stampa director Giulio Anselmi, in comments published in Corriere della Sera newspaper.