Hundreds of soccer matches have been fixed in a global betting scam run from Singapore, police said on Monday, in a blow to the image of the world's most popular sport and a multi-billion dollar industry.

About 680 suspicious matches including qualifying games for the World Cup and European Championships, and the Champions League for top European club sides, have been identified in an inquiry by European police forces, the European anti-crime agency Europol, and national prosecutors.

"This is a sad day for European football," said Rob Wainwright, director of Europol. "This is now an integrity issue for football. Those responsible for running the games should hear the warnings."