The 150-cap former international believes that such activities denigrate the name of the sport which he loves.
"Football is played around the world, and there is always some black sheep trying to take advantage of this beautiful sport illegally," he told Sky Germany. "I have never been involved with such things because I have always believed in the positive side of football. But you can see what is happening all around the world of football."
A profit of around 8 million euros was allegedly made by the betting syndicate, which is believed to be based in Asia.