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 on Tuesday as a widening inquiry into soccer corruption targeted Milan's last title campaign.
Four others were arrested in a 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.
Gattuso said he was ''angry and offended.''
''This stuff is absurd and incredible,'' Gattuso told SportMediaset TV. ''I don't even know what it means to fix a match, I wouldn't know where to start. Let's see what happens now but I'm certain that everything will be cleared up.''
Brocchi's agent, Davide Lippi, said his client was innocent.
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 of the case involving more than 50 people arrested since mid-2011.
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 coach in September. Brocchi is currently coaching in AC Milan's youth program.
Police said in a statement that the arrests were carried out in Milan, Bologna, Rimini and Messina.
Di Martino said some 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, lamenting that past arrests have not made much of an impact.
''There certainly were not big reactions in Italy, considering that things continue to go on like before,'' the prosecutor added.
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, plus games involving Juventus and Inter Milan.
Milan won its last Serie A title in 2011.
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 Last Bet operation started 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.
Follow Andrew Dampf at http://twitter.com/asdampf