Twelve leaders of hardcore Juventus “ultra” football fan groups have been arrested on suspicion of criminal association, money laundering, violence and aggravated extortion in connection with ticket sales.

The suspects allegedly threatened to sing racist chants during matches if the Italian Serie A champions’ ticketing officials did not hand over blocks of reduced-price tickets that the ultras could then sell on to fans. The threats came after Juventus stopped distributing blocks of tickets for sale in 2017. Clubs are fined and can have points deducted over racist chanting.

The investigation by Turin prosecutors, which was carried out with the help of police forces across central and northern Italy, began last year after a complaint by the club. The investigation was linked to alleged mafia infiltration into the ultras’ ticket touting.

Police said those arrested had established a “widespread criminal strategy to ‘restore’ lost favours”.

The suspects allegedly threatened to sing racist songs if they were not given cut-price tickets to sell on. Photograph: Luca Bruno/AP

Juventus was fined in 2017 and its president, Andrea Agnelli, banned for a year over an alleged scheme that involved giving tickets to ultras in exchange for guaranteeing peace in the stadium.

Italy’s ultras tend to be well organised, extremely violent and racist. A murder investigation was launched in August after Fabrizio Piscitelli, a leading member of the Lazio ultras, was shot dead in a park in Rome. The Lazio ultras, also known as Irriducibili (irreducibles), have been linked to several acts of racism and antisemitism that have blighted the Serie A club in recent years.

In April, they paid tribute to the fascist dictator Benito Mussolini in Milan before an Italian Cup match between Lazio and AC Milan. Two AC Milan players were also subjected to racist chants by fans during the game.

The arrests on Monday came after an Italian football journalist was sacked for making on-air racist remarks about the Inter Milan player Romelu Lukaku. Luciano Passirani was a guest on the TV show Qui Studio a Voi Stadio when he said the only way to stop Lukaku was to give him “10 bananas to eat”.