Swiss federal prosecutors opened criminal proceedings related to the awarding of the 2018 and 2022 World Cups, throwing FIFA deeper into crisis only hours after nine former or current officials were among 14 people indicted Wednesday in a separate U.S. corruption probe.
FIFA, meanwhile, said Friday's presidential election would go ahead as planned, with Sepp Blatter going for a fifth term. UEFA on Wednesday called for postponement of the FIFA presidential election and said it may boycott the congress.
Blatter was not named in either investigation. FIFA also ruled out a revote of the World Cups won by Russia in 2018 and Qatar in 2022.
"As unfortunate as these events are, it should be clear that we welcome the actions and the investigations by the U.S. and Swiss authorities and believe that it will help to reinforce measures that FIFA has already taken to root out any wrongdoing in football," Blatter said in a statement. "Let me be clear: such misconduct has no place in football and we will ensure that those who engage in it are put out of the game."
The Swiss prosecutors' office said in a statement it seized "electronic data and documents" at FIFA's headquarters in Zurich on Wednesday as part of its probe. Swiss police said they will question 10 FIFA Executive Committee members who took part in the World Cup votes in December 2010.
The Swiss investigation of "persons unknown on suspicion of criminal mismanagement and of money laundering" again throws into doubt the integrity of the voting.
The announcement came only hours after seven former or current FIFA officials were arrested and detained by Swiss police pending extradition at the request of U.S. authorities after a raid at a luxury hotel in Zurich.
The U.S. case involves bribes "totaling more than $100 million" linked to commercial deals dating back to the 1990s for football tournaments in the United States and Latin America, the Swiss Federal Office of Justice said in a statement.
The Swiss prosecutors' office said the U.S. probe was separate from its investigation but that authorities were working together.
The Swiss justice ministry said U.S. authorities now have 40 days to submit a formal extradition request to Switzerland for six of seven FIFA officials arrested in a FIFA corruption probe, adding that six of those seven plan to fight extradition.
Swiss officials did not name the person who agreed to purse simplified extradition. That person could be handed over to U.S. authorities immediately.
Dozens of officials are in Switzerland for the FIFA congress and presidential election, where Blatter is widely expected to be re-elected to the helm of the governing body of world football. The 209 presidents of FIFA's member federations will vote Friday.
"He is not one of the ones arrested. He is not involved at all," FIFA spokesman Walter de Gregorio told The Associated Press. "We are trying to find out more from the police."
Two candidates in the election, Luis Figo and Michael van Praag, withdrew last week, leaving Prince Ali Bin Al Hussein of Jordan -- FIFA's vice president for Asia -- as Blatter's only challenger.
The Jordanian prince seized on the situation to push his candidacy.
"We cannot continue with the crisis in FIFA, a crisis that has been ongoing and is not just relevant to the events of today,'' Al Hussein said in a statement. "'FIFA needs leadership that governs, guides and protects our national associations. ... Leadership that restores confidence in the hundreds of millions of football fans around the world.''
During a news conference in Zurich, De Gregorio said both the FIFA election and the World Cups would go on as planned: "Russia and Qatar will be played, this is fact today. I can't go into speculation about what will happen tomorrow."
Two current FIFA vice presidents were among those indicted: Jeffrey Webb and Eugenio Figueredo, according to the U.S. Department of Justice. Others indicted include Jack Warner, Eduardo Li, Julio Rocha, Rafael Esquivel, Jose Maria Marin and Nicolas Leoz.
Nine of the 14 who were indicted by the Justice Department are football officials, while four are sports marketing executives, and another works in broadcasting. On Wednesday, FIFA banned 11 from football-related activities, including Webb, Li, Rocha, Takkas, Jack Warner, Figueredo, Esquivel, Marin, Leoz, Blazer and Daryll Warner.
"The indictment alleges corruption that is rampant, systemic, and deep-rooted both abroad and here in the United States," U.S. Attorney General Loretta E. Lynch said in a statement. "It spans at least two generations of soccer officials who, as alleged, have abused their positions of trust to acquire millions of dollars in bribes and kickbacks."
Russian sports minister Vitaly Mutko, who is also a FIFA executive committee member, told The Associated Press "we've got nothing to hide."
"We're prepared to show everything," Mutko said in a telephone interview. "We've always acted within the law.''
Qatari football officials declined to comment.
Blatter had been scheduled to attend a meeting of the Confederation of African Football in a different downtown Zurich hotel, but he canceled his appearance. Al Hussein said it was "a sad day for football," but declined to comment further.
The statement from the Swiss prosecutor's office said the investigation was opened March 10, alleging that at least some of the "unjust enrichment" in relation to the bidding process for the two World Cups took place in Switzerland.
The statement also said that since FIFA's head office is in Switzerland, "investigations are being carried out on the suspicion of criminal mismanagement." There are also "suspicions of money laundering through Swiss bank accounts."
The New York Times reported that more than a dozen plainclothes Swiss law enforcement officials arrived unannounced at Zurich's Baur au Lac hotel in the early hours of Wednesday morning as leaders of FIFA gathered for their annual meeting.
The dawn raids at the hotel were coordinated "in such a way as to allow the procurement of any criminally relevant data in an effective manner, and to avoid any possible collusion."
The statement continued: "These measures were carried out simultaneously as a large number of persons involved in allocating the World Cups were currently in Zurich. These legal actions concern two criminal procedures conducted separately by the OAG and the US Attorney's Office for the Eastern District of New York.
"The Swiss and US law enforcement authorities are not conducting any joint investigations, but are coordinating their respective criminal proceedings.
"On 18 November 2014, FIFA had filed criminal charges against persons unknown with the OAG. Therefore, the Swiss proceeding is aimed at persons unknown, with FIFA as the injured party. With this procedure, the OAG is contributing to the struggle against corrupt behaviour and money laundering."
In Florida, a small group of agents from the FBI and IRS executed search warrants at CONCACAF headquarters in Miami Beach. Neither agency offered comment on the investigation.
CONCACAF reported itself to U.S. tax authorities in 2012. Then based in New York, the organisation had not paid taxes over several years, when Warner served as its president and its secretary general was Chuck Blazer of the United States.
Warner, who is from Trinidad and Tobago, left the organisation in 2011 to avoid FIFA sanctions in a bribery scandal during that year's presidential election.
Blazer left in 2013 and has pleaded guilty to several charges, the U.S. Justice Department said in Wednesday's statement.
Information from The Associated Press was used in this report.