Police said they would investigate after a letter addressed to Pope Francis that contained bullets was intercepted by postal workers in Italy.
The suspicious envelope, which contained three bullets, was found overnight at a mail sorting facility in a Milan suburb, police said.
It had been sent from France.
The envelope was addressed by hand in pen to: “The Pope, Vatican City, St. Peter’s Square, Rome,” and contained three bullets presumed to be for a pistol and a message referring to financial operations at the Vatican.
An investigation is ongoing.
There was no immediate comment from the Vatican.
Pope Francis has been recuperating after a 10-day stint in hospital for colon surgery in July.
He plans to visit Hungary and Slovakia next month, along with a quick stop in Glasgow, Scotland, in November to participate in the COP26 climate conference.