Madrid, Sep 22 (IANS): The prosecution in Madrid on Tuesday opened an investigation to determine whether German champions Bayern Munich's Spanish defender Xabi Alonso has committed tax fraud after a complaint was filed by the tax authorities.

Prosecution officials said that information regarding the case is currently being studied to determine the charges against the former player of Spanish heavyweights Real Madrid, reports Efe.

Media reports on Tuesday also said investigations are related to undeclared income from publicity and image rights, when Alonso was playing for English side Liverpool from 2010 to 2012, allegedly using overseas companies.

Before joining Real Madrid Alonso played for Liverpool, along with his former Argentine teammate Javier Mascherano, currently with champions FC Barcelona, and it is during this time that they are alleged to have purchased two companies, one in Portugal and the other in Miami, United States.

The prosecution will also involve Mascherano in the investigations.

Alonso tweeted on Tuesday that he has "always" complied with his tax obligations.

He also emphasised he would respond and defend his interests through taking appropriate measures, stressing that he will prove that all his tax obligations "have been fulfilled scrupulously."