Former AC Milan and Italy midfielder Gennaro Gattuso has been placed under investigation for match-fixing, while four more people have been arrested in an early morning police sweep in Italy.

Cremon prosecutor Roberto Di Martino, who has been leading the Last Bet operation for three years, confirmed to The Associated Press that Gattuso and retired Lazio player Cristian Brocchi allegedly were part of a ring that fixed Serie A and other Italian matches at the end of the 2010-11 season.

The four people arrested are Salvatore Spadaro, Francesco Bazzani, Cosimo Rinci and Fabio Quadri; each of whom allegedly helped connect fixers to players.

Gattuso's agent has said his client is shocked by the allegations.

'Gennaro is stunned by the news,' Andrea D'Amico told Press Association Sport. 'I spoke to him and he is returning home (to Milan).

'We are remaining calm and we have to be patient and see how the investigation develops.

'However, just because he is under investigation does not mean anything, for all we know this could be just false allegations.

'Sometimes when you are a famous player, it is very easy for your name to appear and to be a target.

'We will wait and see how the situation develops.'