Atalanta president Ivan Ruggeri is stunned by the silence of rivals after he publicly condemned his club's ultras this week.
"I have to say I am astonished by this. I didn't expect messages of solidarity, but at least some kind of reaction from everyone. All must do their duty.
"This is the time to say enough and if we don't do it now, it means we are aware of everything that is happening and accept it.
"I cannot allow it to go on and as far as I am concerned if things don't change I am prepared to close down football in Bergamo. I am very disappointed in the authorities so far and don't know whether to trust them."