Lazio have labelled UEFA's decision to force them to play two games behind closed doors for perceived racist behaviour as 'absurd'.
The latest sanctions follow the Serie A side's Europa League match against Borussia Moenchengladbach.
The capital club have already been found guilty of similar offences after their games against Tottenham and Maribor in the group stage of the competition.
But Lazio president Claudio Lotito says being forced to play their upcoming games against Stuttgart without fans is unfair and that the club will not accept the punishment.
"We cannot as a club be penalised for the mistakes of a small minority (and) we will lodge an appeal," Lotito told RaiSport.
"Lazio did everything we could and should have done to stop this from happening.
"It seems absurd to me that we have to play behind closed doors, which will seriously damage the club economically and stop the fans from participating in this event.
"We must distinguish between the delinquents who act on their own volition and those fans who express themselves in a civilised fashion."