Pope Francis is at risk of mafia retribution as a result of his determination to clean up corruption and cronyism within the Catholic Church, one of Italy's best known anti-mob prosecutors said.
Nicola Gratteri, who has lived under police protection for nearly 25 years, said the Jesuit Pope's campaign to tackle graft was upsetting powerful crime organisations in Italy, which have in the past enjoyed a cosy relationship with the Catholic hierarchy.
"Those who have up until now profited from the power and wealth deriving from the church are now nervous, agitated. The Pope is dismantling centres of economic power in the Vatican," said Mr Gratteri (55), who has spent his career fighting the 'Ndrangheta mafia of Calabria in the far south of Italy.
"I don't know if organised crime is in a position to do something, but certainly they are thinking about it. It could be dangerous. If the godfathers can trip him up, they would not hesitate to do so," he told 'Il Fatto Quotidiano', an Italian daily.
The church had often turned a blind eye to the activities of mafia groups like the 'Ndrangheta, said Mr Gratteri, who earlier this year was appointed by Enrico Letta, the prime minister, to a national task force that was ordered to come up with new ways of combating organised crime.
"For years, the mafia has laundered money and made investments, taking advantage of the connivance of the church," he said.
He gave a few examples, including "a bishop of Reggio Calabria who refused to criticise a mafia godfather even after he was definitely convicted by the Supreme Court".
For all their brutality and disdain for the law, the vast majority of mafiosi regard themselves as Catholics.
"We did a survey of prisoners in jail and 88pc of mafia guys said they were religious. A gunman from the 'Ndrangheta will pray before killing someone."
Allegations of collusion between organised crime and elements within the Catholic hierarchy extend back to the early 1980s when Roberto Calvi, who was nicknamed "God's banker" for his links to the Vatican, was found hanging beneath Blackfriars Bridge in London.
One of the prevailing theories about his death in 1982 was that Calvi, who was the chairman of an Italian bank, was murdered by Cosa Nostra, the Sicilian mafia, as punishment for losing money entrusted to him by mobsters.
On Tuesday, police in Rome placed under state control a hotel on suspicion that it was owned and run by the 'Ndrangheta.
The four-star Grand Hotel Gianicolo was formerly a monastery that was bought from the church in the 1990s with allegedly dirty money.
On Monday, the Pope gave a fiery sermon against corruption, quoting a passage from the Bible in which Jesus said sinners deserve to be tied to a rock and thrown into the sea.
In May, during an address in St Peter's Square in Rome, he strongly criticised Italy's four mafia organisations for "exploiting and enslaving people", calling on gangsters to repent.
"I think of all the pain of men, women and even children who are exploited by many mafias," Pope Francis said during his weekly address.
"They are forced to do work that makes them slaves, like prostitution. Behind all this slavery there are mafias."
He was speaking a day after the beatification of Don Giuseppe Puglisi, a Catholic priest who was murdered by Cosa Nostra in 1993. (© Daily Telegraph, London)