Italian authorities said the Calabrian mafia, the 'Ndrangheta, was behind a match-fixing ring involving some 30 football clubs and scores of people across the country.
Police detained more than 50 people, including football players, coaches and club owners, in a series of raids in 21 provinces in the latest investigation to shake Italy's favourite sport.
Another 20 people were under investigation over their alleged ties with two criminal networks which, according to prosecutors in the southern city of Catanzaro, were able to fraudulently influence the result of dozens of matches of Italy's third and fourth division, pocketing millions in betting profits.
"[They] were plotting to extend the fixes to Serie B and bigger matches," prosecutor Vincenzo Antonio Lombardo told a press conference.
The operation, codenamed in English "Dirty Soccer", stemmed from a linked anti-mafia probe on the alleged illicit dealings of 'Ndrangheta mobster Pietro Iannazzo.
Taping his phone calls, detectives learned about his dubious interest in a small football club, Neapolis, and went on to uncover a massive match-fixing network that they said also had ties and investors in Serbia, Slovenia, Malta, Turkey and Kazakhstan.
The investigation shows "how the ramifications of the 'Ndrangheta have reached a high level not only in the classic areas where criminal gangs operate but also in the world of sports," said anti-Mafia investigator Renato Cortese.
Fixers would bribe club owners or key players involved in a specific fixture with up to €60,000 (£43,000, $67,000) to make sure the score would go the way they wanted.
Prosecutor Giovanni Bombardieri said violence was also involved. "There have been cases of abduction and beatings. Some seriously dangerous people are implicated," he said.
The criminal networks allegedly fixed the results of almost 30 matches from September 2014 to April 2015, involving a series of teams police said included Pro Patria, Barletta, Brindisi, L'Aquila, Torres, Vigor-Lamezia, Santarcangelo, Sorrento, Montalto, Puteolana, Akragas and San Severo.
Those arrested are facing a series of charges including criminal association aimed at sports fraud and mafia links.
"Probably in situations like these there needs to be better control of the leagues and more checks required," Italian coaches' association president Renzo Ulivieri told Gazzetta dello Sport. "If this is the situation, we're facing an absolute emergency."
No celebrity footballers or renowned sport personalities were initially said to be involved in the investigation, differing from the previous gambling scandal to hit Italian football.
In 2011 several Seria A players were among more than 100 people placed under investigation as part of the so-called operation Last Bet.