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."

Soccer is played worldwide. The World Cup and Europe's Champions League are beamed worldwide and generate billions of dollars for national associations, clubs and broadcasters.

The matches in question were played between 2008 and 2011, the investigators said. About 380 of the suspicious matches were played in Europe, and a further 300 were identified in Africa, Asia and Latin America.

Corruption linked to Asian betting syndicates and organized crime has long been seen as a threat to the game, but Monday's announcement underlines the scale of the problem.

Ralf Mutschke, director of security for world soccer's governing body, FIFA, said sports bodies and prosecutors needed to work more closely together.

"The support of law enforcement bodies, legal investigations and ultimately tougher sanctions are required, as currently there is low risk and high gain potential for the fixers," said Mutschke, a German former police officer.

Last year the head of an anti-corruption watchdog estimated that $1 trillion is gambled on sport each year - or $3 billion a day - with most coming from Asia and wagered on soccer matches.

Singapore connection

A German investigator described a network involving couriers ferrying bribes around the world, paying off players and referees in the fixing, which involved about 425 corrupt officials, players and serious criminals in 15 countries.

"We have evidence for 150 of these cases, and the operations were run out of Singapore with bribes of up to 100,000 euros ($135,000) paid per match," said Friedhelm Althans, chief investigator for police in the German city of Bochum.

Singapore police said last month that they were helping Italian authorities to investigate alleged soccer match fixing involving a Singaporean, but said he had not been arrested or charged with any offense there.

German investigators said international matches were implicated, as were games in Turkey, Germany, Switzerland, Belgium, Croatia, Austria, Hungary, Bosnia, Slovenia and Canada. Suspicious games had also been identified in Africa, Asia and Latin America.

Fourteen people have already been convicted in Germany in connection with the investigation.

Austrian prosecutors are investigating 20 people, including players, on suspicion of fraud and money laundering linked to fixing and betting on soccer matches, a spokesman for prosecutors in the city of Graz said.

Investigators said no names of players or clubs would be released while the investigation proceeded. However, the fixing also included top flight national league matches in several European countries, as well as two Champions League matches, including one played in Britain.

UEFA, European soccer's governing body, said it expected to receive further information from Europol in the coming days.