Swiss police on Wednesday staged a dawn raid on a Zurich hotel and detained six top football officials as part of a US investigation into tens of millions of dollars of bribes, Swiss authorities and media reports said.
All six could be extradited to the United States with the shock arrests coming only two days before FIFA president Sepp Blatter seeks reelection as head of football's world governing body in a campaign overshadowed by scandal.
Swiss police, meanwhile, raided the headquarters of FIFA in Zurich, seizing documents and data, the Swiss attorney-general's office said.
The raids were part of an investigation already underway into money laundering and fraud involving FIFA's awarding of the 2018 and 2022 World Cups to Russia and Qatar respectively, a statement said
Jeffrey Webb, a vice president of FIFA, was among those detained in the dawn police raid, according to the New York Times.
Swiss police in plain clothes took the room keys from the reception at the Baur au Lac hotel and went to the rooms of the six, the New York Times said.
The operation was carried out peacefully, it added.
The newspaper added that Eduardo Li, an official from Costa Rica, was also seen being led away.
The Swiss justice ministry said only that six football officials had been detained following a request from the US Attorney's Office for the Eastern District of New York.
It said they were suspected of accepting "bribes and kick-backs between the early 1990s and the present day."
A ministry statement said that "representatives of sports media and sports marketing companies were alleged to be implicated in payments to top football organisation officials," including delegates of FIFA and people linked to the world body.
It said the bribes were paid "in exchange for the media rights and the marketing rights for competitions in the United States and South America."
Webb is the head of the CONCACAF federation for North and Central America and the Caribbean.
The six were being held pending extradition, the statement said.
"According to the US request, these crimes were agreed and prepared in the US, and payments were carried out via US banks," the statement said.
FIFA leaders, including Blatter, are staying at the luxury Baur du Lac ahead of the world body's annual congress starting Thursday. It will elect a president on Friday.
Blatter made no immediate comment. He is a strong favourite to win a fifth term but it was not known whether the arrests would impact the election.
Blatter was not a target of the US investigation, the New York Times said.
Media gathering at the hotel on Zurich's lakeside were pushed outside.
FIFA officials leaving the hotel following the early-morning raid refused to comment.
A FIFA spokeswoman told AFP international football's top body was aware of the reports about the arrests.
"We are seeking to clarify the situation. We will not comment at this stage," she said.
The organisation scheduled a press conference for 0900 GMT in Zurich which will also be streamed live on its website.
In May, Blatter denied he was a target of an FBI corruption investigation and that he had no fear of going to the United States.
He said he would probably go in 2016 for a football tournament there.
The denial came after an ESPN television documentary said the Swiss official stayed away from the US over a FIFA investigation.
But Blatter, who has led FIFA since 1998, has continually had to steer the multi-billion dollar world body through corruption storms.
The latest has been over the award of the 2018 and 2022 World Cups to Russia and Qatar.
Qatar has strongly denied any wrongdoing linked to its bid. But a former FIFA vice president from the Gulf state was banned for life from FIFA because of corruption.
A former US attorney, Michael Garcia, investigated the World Cup bids. He left FIFA because it refused to fully publish his report.
Prince Ali bin al Hussein of Jordan, a FIFA vice president, is standing against Blatter in Friday's election. He called Wednesday's arrests a "sad day" for football.
He and European federation chiefs say a change of leadership is now urgently needed to save FIFA's tainted image.