Catholic groups on Tuesday accused Italy's Church of an "institutional failure" to confront clergy sexual abuse, and demanded an independent national inquiry mirroring ones conducted in France and Germany.

A collective of nine groups - seven headed by women - issued the demand during the launch of a campaign called "Beyond the Great Silence" and a hashtag, #ItalyChurchToo, inspired by the international #MeToo movement against sexual harassment.

In an online news conference, Paola Lazzarini, head of Women in the Church, called for the opening of the archives of "all dioceses, convents and monasteries", damages for victims and the uncovering of the truth, "however painful".

Globally, revelations of sexual abuse by clergy have so far cost the Church hundreds of millions of dollars in compensation.

The Italian campaign aims to increase public pressure on the Church and the government for a national inquiry going back decades, and rejects assertions from some Italian Catholic leaders that the Church has the resources to do the work itself.

"Only independent investigations (elsewhere) have overcome the Church's resistance to recognise its own institutional failure," said anti-abuse advocate Ludovica Eugenio.

Any Italian investigation "absolutely has to be impartial," added Francesco Zanardi, head of Rete l'Abuso (The Abuse Network).

Pope Francis has expressed shame at the Church's inability to deal with sexual abuse cases and said it must make itself a "safe home for everyone".

The Vatican had no comment on Tuesday.

Italian bishops are due to decide in May on what type of abuse inquiry, if any, the country will hold.

Antonio Messina, 28, one of victims who participated in the news conference, says he was repeatedly abused when he was a minor by an adult seminarian who went on to become a priest.

Without providing details, he said local church authorities in his home town had tried to buy his silence. "The Church is not able to handle this (investigation)," he said.

The German study, released in 2018, showed 1,670 clergymen abused 3,677 minors from 1946 to 2014. The French investigation, released last year and covering seven decades, said more than 200,000 children were abused in Catholic institutions.

Zanardi said the figures would be higher in predominately Catholic Italy because the country has traditionally had many more priests.