By Keith Weir

LONDON (Reuters) - The London Olympics have been free of the match-fixing by criminal gangs that is undermining sports around the globe, an anti-corruption watchdog said on Wednesday.

But success in London should not blind anyone to the threat posed by a toxic combination of organized crime and unlicensed bookmakers, many of them based in south east Asia, the International Centre for Sport Security (ICSS) warned.

"We have no evidence whatsoever in relation to corruption of the Olympic Games," said John Stevens, a former London police chief who is chairman of the ICSS advisory board.

A fixing-free Olympics comes in spite of rampant corruption elsewhere.

"Match fixing has been going on for many years, it's true, but, as of now, in my estimation it's almost out of control internationally," said Chris Eaton, an Australian former policeman who is Director of Sport Integrity at the ICSS,

"International organized crime must be prevented from getting these massive free kicks of cash by corrupting sport and defrauding bookmakers," added Eaton, previously head of security at FIFA, world soccer's governing body.

The ICSS is a not-for-profit organization based in the Qatari capital of Doha which campaigns on sporting security, safety and integrity.

Eaton said an estimated $1 trillion annually was gambled on sport each year - or $3 billion a day.

"Around 80 percent of that money is gambled on football, soccer, and most of that money is either in or to south east Asia," he added.

Eaton said mafia gangs were attracted to match-fixing because it was a way of laundering cash and estimated they were making hundreds of millions of dollars annually.

Problems go right to the top reaches of European club soccer. In Italy, Juventus defender Leonardo Bonucci faces a ban after he was accused of fixing a game when playing for Bari in 2010 while Juventus coach Antonio Conte is also under investigation.

LOSING DELIBERATELY

The International Olympic Committee had been concerned that criminals could target the Olympics and it has set up an information point in the athletes' village helps to warn competitors of the risks.

Athletes can take an online multiple choice test to help drive home the message. It seems to be working so far.

However, the Games have been marred by cases of competitors playing to lose group games to try to engineer an easier route to gold.

Former policeman Eaton and Stevens both praised Olympic officials and badminton's governing body for its tough line in disqualifying eight players from China, South Korea and Indonesia who tried to throw matches for this purpose.

"I congratulate the world badminton federation for its decision to send home teams of players who did not play to form, who played to lose," said Eaton.

He criticized the Japanese women's soccer team for playing for a draw against South Africa to ensure they did not have to move to a different base for their quarter-final.

"It's only a short step from making a decision to underplay for the purpose of maintaining a position on a ladder to saying, let's do it now for a bit of money as well," he said.

(Editing by Matt Falloon; For all the latest Olympic news go to http://www.reuters.com/london-olympics-2012)