The head of the Italian Referees' Association (AIA) has warned of a growing number of attacks and threats to officials and called for action to be taken.
"There's one professional journalist who, on a television show, said that referees 'have declared war on the people, and when you are in war, you don't just whistle, you shoot -- we need to shoot these referees and not let them officiate,'" he said.
"He's been reported and we are awaiting developments. Bullets have been received at AIA headquarters destined for me, the vice-president and the referee designator [Nicola] Rizzoli.
"It's something that the secret service are investigating, together with the interior ministry."
Referee Marco Di Bello has been summoned to a court hearing after some Lazio fans reported him to the justice system following their game against Inter Milan earlier this season.
"He's got to go to court just because he didn't award a penalty," Nicchi said. "He's been summoned by the consumers' association.
"Have you ever seen a Serie A footballer miss a penalty and be sent to court a week later? This is a terrible thing."
Nicchi said reports of violence against referees were landing on his desk every week.
But he stressed that the officials would not go on strike "since that is something that only employees can do, whereas we are made up of 35,000 volunteers."
Nicchi called on the authorities "not to underestimate" the situation and also revealed that officials' expenses for 30,000 games had still not been paid.