Pope Francis I on the balcony of St Peter's Basilica. It is feared he has become a target for Isis militants. (Getty)
Pope Francis I on the balcony of St Peter's Basilica. He has ordered an investigation into the "black sheep" diocese of scandalous Albenga-Imperia. Reuters

Pope Francis has said a scandal-ridden diocese in Italy where priests posted naked photos of themselves on gay websites, raided church coffers and sexually harassed parishioners, must be investigated by the Catholic Church.

The 'black sheep' diocese of Albenga-Imperia has been described by one Italian newspaper as "the most gossiped about diocese in Italy". It has been run for the last 25 years by Bishop Mario Oliveri, now aged 70.

The Pope will reportedly send an "apostolic administrator" to assess allegations that the diocese in the north of the country has hosted a string of "playboy priests" who moonlight as barmen, steal parish funds and get tattooed, the Telegraph reports.

The bishop himself is not accused of any wrongdoing but it understood to have been overly-charitable in recruiting priests will chequered pasts, including trainee priests expelled from seminaries for misconduct.

Pope Francis has already sent an apostolic nuncio, Adriano Bernardini, to conduct a preliminary investigation into the scandals, which include a priest who was found guilty of organising a paedophile prostitution ring and others who posted nude photos of themselves on Facebook and gay sex websites.

Priests in the diocese have also been accused of sexually harassing parishioners, living with gay partners, and stealing Communion money.

Father Luciano Massaferro for example, was sentenced to eight years in prison after being found guilty of sexually abusing an altar boy.

The Vatican was made aware of the scandals by appalled parishioners, including doctor Luisa Bonello, who wrote to the Pope in February before committing suicide.

A Vatican spokesman said the Holy See would not comment on an ongoing investigation.

In an unprecedented move in July, the Pope sanctioned the defrocking of a Catholic archbishop after he was convicted of sexually abusing teenage boys. The man in question, also a former Holy See ambassador, is the most senior person in the Vatican's history to be punished for such a crime.