Pope Francis has come to the aid of an Italian man accusing his former priest of abusing him when he was a child in Naples.

The man, using the alias Diego, accused Father Silverio Mura of sexually abusing him hundreds of times when he was a teenager, according to the Sydney Morning Herald.

Diego, 39, came forward with the allegations in 2009 with no result. The local diocese continued to allow Father Mura to interact with children, and no investigation was conducted. Diego decided to write to Pope Francis directly, and finally received a response.

The Vatican launched an investigation into the claims, and the priest could be defrocked if found guilty. Mura, through a representative of the Diocese of Naples, declined to comment on the case or his guilt or innocence.

The case is one of several in which Francis has intervened to accelerate investigations against clergy accused of abuse. The Pope recently sent an investigator to Kansas City, Missouri to examine charges that a local bishop covered up a priest's sexual misconduct.

"I would say the Pope is very sensitive to all kinds of suffering, and certainly he is sending an indirect message," a senior Vatican official said, speaking on the condition of anonymity. "These kinds of cases will not be tolerated."

Chilean citizens are hoping that the Pope will also intervene in the case of Bishop Juan Barros Madrid, appointed in January to succeed Monsignor Fernando Natalio Chomali Garib.

The bishop is accused of covering up years of paedophilia allegations against Rev. Fernando Karadima, who was sanctioned by the Church in 2011 for child sexual abuse. A judge determined that the charges against Karadima were truthful, although the statute of limitations had expired.

Barros denied witnessing Karadima's crimes, destroying evidence, or otherwise having knowledge of the priest's illicit activities.

Pope Francis travelled to Chile two weeks ago to meet with Church leaders amid controversy over the appointment, but details of the meeting were not released. Barros is scheduled to be formally installed on March 21.