Serie A clubs Atalanta and Chievo will face a disciplinary panel next week over allegations of match-fixing and illegal betting.
An original investigation found that only Serie B clubs were involved, but new information has implicated teams from Italian football's top tier.
The Italian Football Federation has called a total of 18 clubs and 26 people to Rome to answer questions.
If guilty, Atalanta and Chievo will almost certainly be relegated, while players will likely be handed lifetime bans.
A similar case hit Italian football in 2006, when many of the country's top clubs were punished for their part in the scandal.
Juventus were stripped of their two previous league titles, banned for one season from the Champions League and relegated to Serie B.