FIFA president Sepp Blatter wears headphones during a joint news conference with Ofer Eini (not pictured), chairman of the Israel Football Association, in Jerusalem May 19, 2015. [Photo/Agencies]

BILLIONS

The international governing body of football collects billions of dollars in revenue, mostly from sponsorship and television rights for World Cups.

It has persistently been dogged by reports of corruption which it says it investigates itself, but until now it has escaped major criminal cases in any country.

In particular, the decision to award the World Cup to Qatar, a tiny desert country with no domestic tradition of soccer, was heavily criticised by soccer officials in Western countries. FIFA was forced to acknowledge that it is too hot to play soccer there in the summer when the cup is traditionally held, forcing schedules around the globe to be rewritten to move the cup.

Qatar's stock market fell sharply as news of the Swiss investigation emerged. A Russian official said his country would still host the 2018 World Cup.

Three years ago FIFA hired a former US prosecutor to examine allegations of bribery over the awarding of the World Cups to Qatar and Russia, but last year it refused to publish his report, releasing only a summary in which it said there were no major irregularities. The investigator quit, saying his report had been mischaracterised.

Most of the arrested officials are in Switzerland for the FIFA Congress, where Blatter faces a challenge from Jordan's Prince Ali Bin Al Hussein in an election on Friday to lead the organisation. Other potential challengers to Blatter have all dropped out the race.

Prince Ali, who has promised to clean up FIFA if elected to the top job, called it "a sad day for football".

CONCACAF FOCUS

Much of the US enquiry focuses on CONCACAF, whose Trinidadian former boss Warner was regularly dogged by accusations of corruption before he resigned in 2011, at which point FIFA terminated its investigations of him.

A combination of file photos show then FIFA executive member Jack Warner (L, taken May 30, 2011), then Acting President of the South American Soccer Federation (CONMEBOL) Eugenio Figueredo (C, taken April 30, 2013) and then Confederation of North, Central America and Caribbean Association Football (CONCACAF) President Jeffrey Webb (R, taken April 19, 2013). U.S. authorities said nine football officials and five sports media and promotions executives faced corruption charges involving more than $150 million in bribes. Swiss police arrested seven FIFA officials who are now awaiting extradition to the United States. [Photo/Agencies]

US law gives its courts broad powers to investigate crimes committed by foreigners on foreign soil if money passes through US banks or other activity takes place there.

Damian Collins, a British member of parliament who founded the reform group New FIFA Now, said the arrests and could have a massive impact on the governing body.

"The chickens are finally coming home to roost and this sounds like a hugely significant development for FIFA," he told Reuters.

"It proves that Sepp Blatter's promises over the last few years to look into corruption at FIFA have not materialised and because he has totally failed to do this, it has been left to an outside law enforcement agency to do the job and take action."