ROME (AP) - Former AC Milan midfielder Gennaro Gattuso, one of the key players in Italy's World Cup-winning team in 2006, was placed under investigation for match-fixing Tuesday as a widening inquiry into soccer corruption targeted Milan's last title campaign.
Four others were arrested in an early-morning police sweep.
Cremona prosecutor Roberto Di Martino, who has been leading the Last Bet operation for three years, told The Associated Press that Gattuso and retired Milan and Lazio player Cristian Brocchi were allegedly part of a ring that fixed Serie A and other Italian matches at the end of the 2010-11 season.
''About 30 matches, a good part of them involving Serie A, are under investigation,'' Di Martino told the AP.
The four people arrested were Salvatore Spadaro, Francesco Bazzani, Cosimo Rinci and Fabio Quadri. Each of them allegedly helped connect fixers to players, Di Martino said.
More than 50 people have been arrested since mid-2011 in the case.
Di Martino said a couple of the people arrested Tuesday met as recently as this year, suggesting matches continue to be fixed.
''We're seeing clear facts that despite the arrests and investigations, a good part of these people continue to do what they did before,'' Di Martino said later in a news conference.
''There certainly were not big reactions in Italy, considering that things continue to go on like before,'' the prosecutor added.
Gattuso and Brocchi face charges of criminal association with the aim of fraud and sports fraud and had their homes searched. About 20 other people were also placed under investigation.
''Gattuso and Brocchi were connected to the case by the use of phone taps,'' Di Martino said.
Gattuso, who won two Champions League titles with Milan, was fired as Palermo's coach in September. Brocchi is currently coaching in AC Milan's youth program.
''I spoke to Rino and he's (stunned),'' Gattuso's agent, Andrea D'Amico, told the ANSA news agency, using his nickname. ''Right now it's important not to draw any conclusions and rather wait and see why these names are coming out.''
Police said in a statement that the arrests were carried out in Milan, Bologna, Rimini and Messina.
Other former and current players placed under investigation included Claudio Bellucci, Davide Bombardini, Leonardo Colucci, Lorenzo D'Anna, Nicola Mingazzini, Claudio Terzi, Samuele Olivi and Fabrizio Grillo.
The Gazzetta dello Sport reported that Milan matches against Lazio, Chievo Verona and Bari in February and March 2011 were under investigation, along with games involving Juventus and Inter Milan.
Milan won its last Serie A title in 2011.
The Last Bet operation has resulted in more than 100 people placed under investigation in Italy since mid-2011, with suspect matches being looked at by prosecutors in Cremona, Bari and Naples.
The case has led to lengthy bans for former Lazio captains Giuseppe Signori and Stefano Mauri and former Atalanta captain Cristiano Doni. Several clubs have also had points deducted.
Prosecutors have detailed an extensive match-fixing ring stretching as far as Singapore and South America that was allegedly in operation for more than 10 years.
The arrests of 14 people in Singapore in September was hailed as a major breakthrough in the fight against corruption in soccer, with the global network's suspected mastermind among those taken into custody.
The Last Bet operation came only a few years after the 2006 Italian match-fixing scandal, which revealed arrangements with referees and resulted in Juventus being stripped of the 2005 and 2006 Serie A titles.
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