Members of Marc Marquez's Italian fan club will miss the Mugello MotoGP round in May due to concerns over their safety.
The 2015 season turned sour when two-time world champion Marquez was involved in a spat with Valentino Rossi, who dramatically missed out on the title to Jorge Lorenzo.
Tensions between Rossi and Marquez boiled over when the Italian made contact with the Spaniard in Sepang, resulting in the Repsol Honda rider crashing out of the race.
Rossi started the final race of the season in Valencia at the back of the grid as punishment for his actions, giving Lorenzo a golden opportunity to wrap up the title, which he grabbed with both hands.
The pair are set to renew their rivalry this season and Marquez will not be able to count on his usual backing in Mugello.
"We're really very sorry to have to make this drastic decision, but the situation at the moment is not great and the environment is really dangerous," a statement from Marquez's Italian supporters group said.
"We find it shameful that fans can't cheer freely for their rider without running the risk of being threatened, having things thrown at them, or even being spat on - but unfortunately we have arrived at this point.
"We hope that you understand this choice has been taken for the good of the members.
"Already last year, we had threats at Mugello and Misano, not to mention being spat on.
"Unfortunately, there are fans - of every rider - that don't understand that a rivalry between riders doesn't have to lead to a continuous confrontation between the fans in the stands."