Runaway leaders Juventus have been ordered to close the Curva Sud for their next two home Serie A games and been fined €50,000 following the violence that marred Sunday's derby with Torino.
Serie A's disciplinary tribunal made the decision on Thursday after concluding that Juve supporters were responsible for throwing a paper bomb that injured nine people in the Torino section.
The fans were originally blamed for the incident but the tribunal asked for further investigations after media reports that the paper bomb could have been detonated by Torino followers.
The tribunal said in a statement that local authorities had confirmed "the original scenario" in which the device was "launched from the upper tier of the visitors' section occupied by members of the Juventus hardcore supporters".
Torino were also fined €50,000 for failing to prevent Juve fans taking the device into the stadium.
The Curva Sud hosts the hardcore Juve fans and the ruling means they will not be able to watch their team's final two home matches of the season against Cagliari and Napoli.
The leaders, who lost the game 2-1, need a point at Sampdoria tomorrow to clinch their fourth successive Serie A title with four games to spare.
Meanwhile, Filippo Inzaghi has clung on to his job as AC Milan coach following their 3-1 home defeat by Genoa and will stay unless there are any major changes, the club said.
Italian media had reported that Inzaghi could be replaced by youth team coach Cristian Brocchi for the final five matches of the season in an attempt to save the club from further embarrassment.