Swiss guards have stopped and arrested two men who were allegedly trying to deposit fake bond certificates worth trillions of euros in the Vatican bank.
The two suspects, a middle-aged Dutchman and a US citizen, apparently approached the gates to the Vatican City and tried to convince guards that they had an appointment with bank officials.
Wearing business suits and carrying briefcases filled with huge sums in bonds, they told guards that "cardinals were expecting them", according to Financial Guard police Lt Col Davide Cardia.
The men were promptly handed over to Italian police after a quick check by Vatican officials showed they neither had an appointment nor any connections with the Institute for Religious Works, the formal name of the bank, which is behind the tiny city-state's walls and is not open to the public.
The Vatican has been scrambling to upgrade procedures and standards at the bank since a 2010 money-laundering probe.
Mr Cardia said the fake documents purported to be bond certificates for non-Italian companies.
"The sum - worth some €3 trillion (£2.47 trillion) - is impressive, even though it's only symbolic because we're talking about false" certificates, said Mr Cardia, in charge of the financial police's operations in Rome and the surrounding area.
Investigators suspect the men might have planned to use the fake bonds as security to open a hefty line of credit through the Vatican bank.
The Vatican asked Italian authorities to help in the investigation.
Italian police searched the men's room at a hotel near the Vatican and seized stamps and seals used to create the false documents, Mr Cardia said.
Both suspects, whose names were not released by police, had been previously investigated for attempted fraud in Asian countries, Mr Cardia said without elaborating. They were issued citations and released on their own recognisance pending further investigation, since Italian law does not require arrest for investigation of attempted fraud, according to the official. Both are believed to have left Italy.
Additional reporting by the Associated Press