Juventus will have to play their next home Serie A game behind closed doors after fans racially abused Inter Milan striker Mario Balotelli in Saturday's 1-1 draw.
The 18-year-old scored Inter's opener in the top-of-the-table clash and was subjected to chants of "a black Italian does not exist" from sections of the Juve crowd in Turin.
Balotelli, an Italy under-21 international, was born in Palermo but is of Ghanaian descent.
"The sporting judge...considered that in the course of the game and on multiple occasions, fans of the home team, in various sections of the stadium, sang songs which included racial discrimination," a league statement said.
"Juventus are therefore obliged to play one game behind closed doors."
Juve, who host Lazio in an Italian Cup semi-final second leg on Wednesday, said in a statement they would appeal the decision to ban fans from the home game with Lecce on May 3.
Racist abuse is not uncommon in Italian soccer and small fines are usually handed out. However, the seriousness of Saturday's incidents have prompted the authorities to come down heavily on Juve.
The league normally decides on disciplinary action on the Tuesday following weekend games but brought the announcement forward this time.
The statement, in conjunction with the Italian soccer federation, added that the abuse was deplorable and could not be excused as sporting passion.
Italy, home of the world champions, is also battling a hooligan problem and missed out on hosting Euro 2012 partly because of soccer violence.
The Champions League final on May 27 will be held in Rome despite a series of minor stabbings around the Stadio Olimpico there in recent years.
A bid for Euro 2016 was recently launched and federation president Giancarlo Abete does not believe Saturday's racist chanting will affect Italy's chances.
"I express firm condemnation of the episode involving Balotelli. Italian football, however, is not the pits of the world," he told reporters.
Juve president Giovanni Cobolli Gigli apologised on Sunday and said Serie A had to end the culture of racism among fans.
Inter Milan president Massimo Moratti said earlier he would have pulled his team off the field if he had been present at Turin's Stadio Olimpico.
Claudio Ranieri's side, joint second in the league, are almost out of the title race with champions Inter holding a 10-point lead with six games left.
In 2006, twice European champions Juve were demoted to the second division for their involvement in a match-fixing scandal but were promoted back the following season.