The president of the Italian Referee Association (AIA) has revealed that parcels filled with bullets have been sent to him and other members of the body.
Marcello Nicchi said on Thursday that the packages had been sent to him, the AIA's vice president Narciso Pisacreta and referee selector Nicola Rizzoli.
The development comes amid supporter protests over the use of the video assistant referee (VAR), introduced in Serie A this season with mixed results.
In March, hundreds of angry Lazio fans appeared outside the Italian football federation's offices in Rome, claiming that their team had been the victim of numerous mistakes by officials and VAR this term.
At a press conference, Nicchi condemned recent comments made by a television journalist which claimed that referees had "declared a war against the people".
"There is a journalist who said in a broadcast: 'In war you do not play the whistle, you are shooting. You have to shoot the referees and not allow them to referee,'" Nicchi is quoted by BBC Sport as saying. "This is the consequence."
VAR is also being used in Germany's Bundesliga and Major League Soccer in the United States, as well as being trialled in the latter stages of the EFL Cup and FA Cup, and will be in use at the World Cup this summer.
