(CNN) -

Recent revelations in print and now on television by convicted match fixer Wilson Raj Perumal are once again throwing the spotlight onto match-fixing in soccer.

Coercing players, officials and administrators into rigging matches has netted fixers millions of dollars while soccer is left counting the cost to its integrity.

How big is the problem?

It's widespread, says Terry Steans, who has worked as an investigator for soccer's world governing body, FIFA.

"I never thought it would be across the globe but it is, and that's the most surprising thing to me (along with) the consummate ease with which fixers gained access to football," Steans told CNN.

In February last year, the European Union's law enforcement agency, Europol announced that 680 matches (380 of them in Europe) played between 2008 and 2011 were under suspicion of being rigged.

"This is the work of a suspected organized crime syndicate based in Asia and operated with criminal networks around Europe," Rob Wainwright, director of Europol said following an 18-month probe.

Specific matches under scrutiny were not named by Europol, but fixtures include World Cup qualifiers and Champions League ties, they said.

Europe's top domestic leagues have been no stranger to soccer corruption in recent times with notable match-fixing scandals erupting in Germany's Bundesliga in 2005 and Italy's Serie A and B the following season.

But match fixing extends far beyond Europe's borders with scandals uncovered in Asia, Africa and Latin America in recent years.

Investigators say that much of the problem stems from illegal gambling markets in Asia, which are said to turn over billions of dollars every single day.

"Football is by far the largest betting market in the world and by far the most liquid," says Joe Saumarez Smith, a sports betting consultant.

Fixers like to target soccer because there are a lot of matches played, he says. But there are other reasons.

"A lot of players are not very well paid and, particularly in the African leagues, they don't get paid ... so match-fixing becomes more attractive," Saumarez Smith says.

How do you go about fixing soccer matches?

With alarming ease, if you believe Perumal.

"I've fixed matches with just a single player," he says. "But, of course, you would like to have the goalkeeper, we would like to have the defenders, then the striker ..."

Perumal told CNN that a fix will often start with one player who is offered money to throw a game. If they are happy to play ball, the match fixer will then use the target to sound out other members of the team.

Using a group of players to fix a match is advantageous to the fixer because it improves the chances of getting the desired result.

It's also more difficult to spot says Declan Hill, author of "The Insider's Guide to Match-Fixing in Football."

"You have six players running around trying as hard as they can; and you have five players pretending to run around trying as hard as they can," Hill explained in a piece penned for CNN last year.

"This way, the outsider finds it extraordinarily difficult to figure out what is going on. All they see is 11 players who may or may not be making mistakes."

Referees are also prime targets for match fixers and Perumal would frequently attempt to bribe the man in black. Some referees were ripe for corruption, he claims.

"These are people who are supposed to uphold the laws of the game. But sad to say that, you know, FIFA doesn't really pay these referees that well," Perumal said.

"They get about $1,000 or maybe $1,500 (per game) which is very small money. In my opinion, FIFA should pay them a lot more or they should start to professionalize this officiating."