Officials from Juventus, Lazio and Fiorentina along with Italy's World Cup referee Massimo De Santis are being investigated about potential match fixing.
Fiorentina president Andrea Della Valle, Lazio president Claudio Lotito and Juventus CEO Antonio Giraudo were formally under investigation by Naples magistrates.
Former Football Federation president Franco Carraro, who resigned on Monday, and Juve general manager Luciano Moggi, who is at the centre of the affair, are also under investigation.
Naples public prosecutor Giovandomenico Lepore declined to give names but told that 41 individuals were now formally under investigation including referees, federation officials and a journalist.
The Naples magistrates are looking into suspicions of 'criminal association' and 'sporting fraud.'
In Italy, investigations by public prosecutors do not necessarily lead to criminal charges.
Lepore confirmed media reports that the investigation was looking into 19 Series A matches from last season and one game from the second tier Series B.
Six-times European champions AC Milan are among the other clubs who feature in the investigation, he said.
The first formal hearing of the investigation will take place on Monday in Rome when Moggi will be questioned, Lepore said.
{{/usCountry}}The first formal hearing of the investigation will take place on Monday in Rome when Moggi will be questioned, Lepore said.
{{/usCountry}}The scandal erupted last week when newspapers published transcripts of Moggi's telephone conversations with senior federation officials regarding refereeing appointments.