Soccer is falling under a cloud of suspicion as never before, sullied by a multibillion-dollar web of match-fixing that is corrupting increasingly larger parts of the world's most popular sport.

Internet betting, emboldened criminal gangs and even the economic downturn have created conditions that make soccer - or football, as the sport is called around the world - a lucrative target.

Known as ''the beautiful game'' for its grace, athleticism and traditions of fair play, soccer is under threat of becoming the dirty game.

''Football is in a disastrous state,'' said Chris Eaton, director of sport integrity at the International Centre for Sport Security. ''Fixing of matches for criminal gambling fraud purposes is absolutely endemic worldwide ... arrogantly happening daily.''

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EDITOR'S NOTE: This story is part of a six-month, multiformat AP examination of how organized crime is corrupting soccer through match-fixing.

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At least 50 nations in 2012 had match-fixing investigations - almost a quarter of the 209 members of FIFA, soccer's governing body - involving hundreds of people.

Europol, the European Union's police body, announced last week that it had found 680 ''suspicious'' games worldwide since 2008, including 380 in Europe.

Yet experts interviewed by The Associated Press believe that figure may be low. Sportradar, a company in London that monitors global sports betting, estimates that about 300 soccer games a year in Europe alone could be rigged.

''We do not detect it better,'' Eaton said in an interview with the AP. ''There's just more to detect.''

Globalization has propelled the fortunes of popular soccer teams like Manchester United and showered millions in TV revenue on clubs that get into tournaments like Europe's Champions League. Criminals have realized that it can be vastly easier to shift gambling profits across borders than it is to move drugs or other contraband.

''These are real criminals - Italian mafia, Chinese gangs, Russian mafia,'' said Sylvia Schenk of corruption watchdog Transparency International.

Ralf Mutschke, FIFA's security chief, admits that soccer officials had underestimated the scope of match-fixing. He told the AP that ''realistically, there is no way'' FIFA can tackle organized crime by itself, saying it needs more help from national law enforcement agencies.

''The scale is such that no country can deal with the problem on its own,'' said EU Sport Commissioner Androulla Vassiliou.

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Gambling on sports generates hundreds of billions of dollars a year, and up to 90 percent of that is bet on soccer, Interpol chief Ronald Noble told the AP. Eaton, the former FIFA expert, has cited an estimated $500 billion a year.

Match-fixing - where the outcome of a game is determined in advance - is used by gambling rings to make money off bets they know they will win. Matches also are rigged to propel a team into a higher-ranking division where it can earn more revenue.

FIFA has estimated that organized crime takes in as much as $15 billion a year by fixing matches. In Italy alone, a recent rigging scandal is estimated to have produced $2.6 billion for the Camorra and the Mafia crime syndicates, Eaton said.

Soccer officials are well aware that repeated match-fixing will undermine the integrity of their sport, driving away sponsors and reducing the billion-dollar value of lucrative TV contracts. FIFA earned $2.4 billion in broadcast sales linked to the 2010 World Cup in South Africa and already has agreed to $2.3 billion in deals tied to the 2018 World Cup in Russia.

FIFA President Sepp Blatter has proclaimed ''zero tolerance'' for match-fixing. Computer experts working for FIFA and UEFA - the European soccer body - monitor more than 31,000 European games and thousands of international matches every year, trying to sniff out the betting spikes that can reveal corruption.

So far, however, sports authorities are ''proving to be particularly helpless in the face of the transnational resources'' available to organized crime, according to a 2012 study on match-fixing. The report warned that the risk of soccer ''falling into decay in the face of repeated scandals is genuine and must not be underestimated.''

Match-fixing has been around for decades, of course, and is not limited to soccer. It has also infected sports like cricket, tennis, horse racing and even volleyball. The U.S. has its own sordid history of gambling scandals, from baseball's Black Sox in the 1919 World Series to a handful of point-shaving schemes in college basketball over the years, to an NBA referee taking money from a professional gambler for inside tips on basketball games, including some that he officiated in 2007.

Still, nothing approaches the scale of the allegations now hitting soccer because of the sheer number of games played and the enormous Asian betting interest in European games, according to David Forrest, an economist at the U.K.'s University of Salford Business School, one of the co-authors of the 2012 report.

In January alone, FIFA banned 41 players in South Korea from soccer for life due to match-fixing. That follows 51 worldwide bans last year - 22 of them for life.

Eaton attributes the surge in match-fixing to an exponential rise in online gambling - ''at least 500 percent, and likely far more'' - in the last decade.

Criminals have targeted every level of the game: the World Cup, regional tournaments such as the Champions League, high-powered divisions like England's Premier League and Italy's Serie A, ''friendly'' exhibition contests between national teams, all the way down to semipro games.

Match-fixing has also branched out from traditional hotbeds of corruption - Asia and the Balkans - to places like Canada, Finland and Norway, among the least corrupt nations in the world.

And with the rise of online spot betting - wagers made during the game - criminal gangs can also make money on bets like how many goals are scored, when they are scored, or who will take a penalty kick.

These live bets can ''be particularly advantageous for criminals,'' according to Forrest's report, because they increase the number of wagers placed on the same fixed game.

The vast majority of the world's wagering originates in Asia, according to Forrest, but its own bettors shun that continent's games because Asian soccer has been so corrupt for years.

In 2011, China's main TV network refused to broadcast the country's soccer games because match-fixing was so widespread. Last year, two former heads of China's soccer federation were sentenced to 10 1/2 years in prison.

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As former Balkan warlords and Chinese businessmen have discovered, owning a club means players don't need to be paid extra to fix matches; they can just be ordered to lose.

''There is an increasing worry about gangs taking over football clubs as a way to further match-fixing ... and then they could also use the club to launder money,'' Forrest said.

An American diplomatic cable released by WikiLeaks quoted the U.S. Embassy in Bulgaria as reporting that ''Bulgarian soccer clubs are widely believed to be directly or indirectly controlled by organized crime figures who use their teams as a way to legitimize themselves, launder money and make a fast buck.''

In Turkey last year, 93 people went on trial for match-fixing - and only 14 of them were players.

Serbian player Boban Dmitrovic says he saw many times where two Serbian clubs simply agreed upon the outcome in advance.

''Right before the match, a note was handed to the players. They had to cooperate because their careers would be jeopardized,'' Dmitrovic told FIFPro, the soccer players' union.

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In the past, the perception was that greedy players were behind match-fixing. Yet a study of eastern Europe by the FIFPro union portrayed a region where players often are not paid for months and are intimidated, blackmailed or beaten up.

Many said they had been approached by match-fixers - an average of 11.9 percent, with spikes in Greece (30 percent) and Kazakhstan (34 percent). In Russia - host of the 2018 World Cup - about 10 percent of players had been approached to throw a game.

Zimbabwe's national team players were threatened at gunpoint in the dressing room and ordered to lose matches by their own soccer officials in 2009, the country's new federation chief, Jonathan Mashingaidze, said in an interview.

In Italy, a goalkeeper under pressure from organized crime to fix a game in 2010 resorted to drugging several teammates so they would play badly. They did - and one even crashed his car after the match, prompting a police investigation that uncovered the fix.

Former player Mario Cizmek of Croatia says he agreed to fix one match in 2011 after he and his teammates had not been paid by his club for more than a year. That led to repeated demands by the fixer, a well-known former coach who used to drink at the same bar as Cizmek's team. It was a classic case of a trusted acquaintance approaching a player to throw a match - a method that Forrest's report says is used often.

''As a sportsman, I know I destroyed everything, but at the time I was only thinking about my family and setting things right,'' Cizmek said.

Now broke and divorced, he has been sentenced to 10 months in jail by a Zagreb court.

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Because scoring in soccer is so low, its referees have an outsized influence on the game.

Tainted referees are believed to be at the heart of one or more games involving South Africa in 2010, with a FIFA report in December finding ''compelling evidence'' of match-fixing.

In 2011, two matches in the Turkish beach resort of Antalya - one between Bolivia and Latvia, the other between Bulgaria and Estonia - appeared suspicious when all seven goals came from penalty kicks awarded by referees. The German magazine Stern later reported that $6.9 million was wagered on the Bulgarian game alone.

FIFA banned the six eastern European officials involved in those games for life.

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Officials who govern the sport can't stop match-fixing by themselves and need the cooperation of law enforcement bodies and governments, said Schenk of Transparency International.

She and the players' union say soccer authorities must also make sure their own ranks are free of corruption and protect whistleblowers better.

''There is a strong link between good governance in the bodies that run sports and the sport organizations' credibility in the fight against match-fixing,'' Schenk wrote in a commentary.

In 2011, Italian defender Simone Farina turned down a fixer's offer of $261,500 to throw a game and reported it to police, setting off an investigation that led to scores of arrests. Despite being honored by FIFA, he found himself shunned by many in Italy who considered him a snitch.

''I said no because my immediate thoughts were of my wife, son and daughter,'' Farina said. ''How could I look them in the eye if I said yes?''

Cizmek - the Croatian player who said he took $26,100 but handed back all but $650 to police - says his scars from match-fixing will last a lifetime.

''This turned my life upside down,'' he said.

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John Leicester in Paris, Graham Dunbar in Geneva, Gerard Imray in Johannesburg, Mike Corder in Amsterdam and Menelaos Hadjicostis in Nicosia, Cyprus, contributed to this report.

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Norman-Culp is AP's Assistant Europe Editor in London. Prior to that, she covered FIFA for AP in Zurich. Follow her at snormanculp(at)twitter.com