European investigators said this week they believe the results of hundreds of matches were fixed at club and national level, with some of the key figures alleged to have run the bribery scam out of Singapore.
Interpol, the international police organisation, did not reply to questions from Reuters about the investigation in Singapore, saying it does not comment on specific cases.
But Interpol chief Ronald Noble told Singapore's Straits Times newspaper it would be wrong to assume "that only Asian organised crime is responsible for match-fixing in Europe and around the world".
It would be unfortunate if Singapore's "well-earned anti-crime reputation" suffered from the allegations, he said in remarks published on Wednesday, but added the city-state must show it is serious about tackling the problem.
"Until arrests are made in Singapore and until actual names, dates and specific match-fixing details are given, these organised criminals will appear above the law and Singapore's reputation will continue to suffer," Noble said.
In November, he had said: "In the near future, Singaporeans will be reading about arrests made here in Singapore."
Police in the city-state said on Tuesday they "are assisting the European authorities in their investigations" and that "Singapore takes a strong stance against match-fixing".
Beyond that, Singapore authorities have yet to say anything about the state or scope of the investigation, including whether they are pursuing the main suspect - identified by various media in 2011 - and others listed in Italian court documents.
This is not entirely surprising in a country where the government keeps a tight rein on information - and police may not want to jeopardise their case. But the lack of comment about a global scandal with roots in Singapore contrasts with this week's very public announcement by European investigators.
With the same party in power for five decades, Singapore has long projected itself as a paragon of good governance and clean living in a turbulent region often rife with corruption. But its links to the match-fixing illuminate a darker underside.
Having Singaporeans as key suspects in the scandal was "extremely shocking" but not a total surprise for Jerome, a 43-year-old transportation worker making legal bets on soccer matches at a state-run Singapore Pools outlet.
"I know it's still happening," he said. "Like loan sharks, it's still happening, not being stopped yet."
Chris Eaton, former head of security at soccer's governing body FIFA and now a director at the International Centre for Sport Security, said Singapore was "either being very cautious, very thorough or they don't have enough to go on".
"I don't know why they appear to not be doing anything but I hope they are," he said. "I'm sure they're doing their best to limit embarrassment. Now they're obligated to respond to the mounting international evidence against Singaporean gangs."
Sources close to the Football Association of Singapore (FAS) said it was assisting police and the city-state's anti-corruption bureau.
"It is a global problem and FAS will continue to work closely with the relevant authorities, both at the domestic and international levels, to combat match-fixing and football corruption aggressively," the association said in a statement.
Singapore hosted an Interpol-sponsored meeting in November of about 50 international sports integrity experts to discuss match-fixing and how to combat corruption.
It is set to have even tighter ties with Interpol when the international body opens a new global complex in the city-state in 2014 that will house a FIFA anti-corruption training centre.
"There are illegal betting syndicates operating across Asia," said B.C. Tan, head of organised crime research at World-Check, a risk analysis firm owned by Thomson Reuters.
"There has to be collective effort from law enforcement agencies in Asia and beyond to address this issue."
During the 2010 World Cup, links between organised crime and illegal betting in Asia came to the fore when Interpol coordinated an operation that led to the arrests of 5,000 people and the seizure of nearly $10 million.
An Interpol statement at the time said "police across China (including Hong Kong and Macau), Malaysia, Singapore and Thailand identified and raided nearly 800 illegal gambling dens which handled more than $155 million worth of bets".
In the allegations unveiled this week, a German investigator described a network of couriers taking bribes around the world to pay off players and referees.
"We have evidence for 150 of these cases, and the operations were run out of Singapore with bribes of up to 100,000 euros ($135,300) paid per match," said Friedhelm Althans, chief investigator for police in the German city of Bochum.
Even when Singapore's actions become known, there is no guarantee the suspects will face all of the charges in Europe.
Singapore allows suspects to be sent only to countries with which it has an extradition treaty. Germany has such a treaty with Singapore but Italy, which made the original complaint about match-fixers manipulating Italian games, does not.
Extradition also requires "common criminality", meaning that a suspect must have allegedly done something illegal in Singapore that gives its police the grounds to detain him.
After the German magazine Stern identified the alleged leader of the Singapore syndicate and published a photo of him in mid-2011, the man said it was a case of mistaken identity.
"Why I'm suddenly described as a match-fixer, I don't know. I'm innocent," he told The New Paper, a Singapore tabloid.
When Reuters called the phone number of that man, as listed in the Italian court documents, the woman who answered was furious. She denied knowing the suspect or having travelled with him when he went to Italy, as detailed in the court documents.
When Reuters journalists went to the suspect's condominium complex, a mid-range development of cream-coloured tower blocks with a swimming pool in northeastern Singapore, security guards shouted at them and would not let them in.
Another Singaporean listed in the documents said he was in Italy at the time indicated by Italian authorities but denied any knowledge of match-fixing. He initially said he was on holiday with his wife but then said he was on business.
"I don't know what you're talking about," he said when asked about the allegations.
A third man identified in the documents confirmed his identity and passport number to Reuters but said he did not think he was in Italy on the dates specified and denied any knowledge of the allegations.
"If the Singaporean police are interested, they'll come to me," he said.
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