ZURICH (AP) — 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 six soccer officials were arrested Wednesday in a separate U.S. corruption probe.

The Swiss prosecutors' office said in a statement they seized "electronic data and documents" at FIFA's headquarters on Wednesday as part of their probe. And 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 against "persons unknown on suspicion of criminal mismanagement and of money laundering" again throws into the doubt the integrity of the voting to award Russia the 2018 World Cup and the 2022 tournament to Qatar.

The announcement came only hours after six soccer 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. FIFA President Sepp Blatter was not among them.

The case involves bribes "totaling more than $100 million" linked to commercial deals dating back to the 1990s for soccer tournaments in the United States and Latin America, the Swiss Federal Office of Justice said in a statement.

It was unclear if the probe was linked to the 1994 World Cup hosted by the United States.

The Swiss prosecutors' office said the U.S. probe was separate from its investigation but that authorities were working together.

Dozens of soccer officials are in Switzerland for the FIFA congress and presidential election, where Blatter is widely expected to win a fifth term at the helm of the governing body of world soccer.

"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."

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.

FIFA called a news conference for 11:00 a.m. (0900 GMT) at its headquarters and the Swiss justice department said it expected to confirm the nationalities of those detained later Wednesday.

Blatter's only opponent in Friday's presidential election, Prince Ali bin al-Hussein of Jordan, said it was "a sad day for football," but declined to comment further.

The arrests were made at the lakeside Baur au Lac Hotel in downtown Zurich, long favored as a place for senior FIFA officials to stay. It was the stage for intense lobbying for votes ahead of the 2018 and 2022 World Cup hosting decisions in December 2010.

Among the people arrested in Zurich was Costa Rica soccer federation president Eduardo Li, according to the New York Times. He was later seen leaving the hotel in a car with law enforcement officials.

Li was elected to the FIFA executive committee in March and will formally join the Blatter-chaired panel on Friday.

The North American regional body, known as CONCACAF, reported itself to U.S. tax authorities in 2012. Then based in New York, the organization had not paid taxes over several years when its president was Jack Warner of Trinidad and Tobago and secretary general was Chuck Blazer of the United States.

Warner left soccer in 2011 to avoid FIFA sanctions in a bribery scandal during that year's presidential election. Blazer left in 2013 and is reported by the New York Daily News to be cooperating with the FBI in a probe of corruption in soccer.

Warner's successor as CONCACAF leader and FIFA vice president, Jeffery Webb of the Cayman Islands, was staying at the Baur au Lac this week. It was unclear if he was detained.

The Swiss Federal Office of Justice said in its statement that U.S. authorities suspect the six arrested officials of having received or paid bribes totaling millions of dollars and that the crimes were agreed to and prepared in the U.S., and payments carried out via U.S. banks.

The FOJ said the U.S. Attorney's Office for the Eastern District of New York is investigating the individuals on suspicion of the acceptance of bribes and kick-backs between the early 1990s and now.

"The bribery suspects — representatives of sports media and sports promotion firms — are alleged to have been involved in schemes to make payments to the soccer functionaries (FIFA delegates) and other functionaries of FIFA sub-organizations - totaling more than USD 100 million," the FOJ statement said. "In return, it is believed that they received media, marketing, and sponsorship rights in connection with soccer tournaments in Latin America."

A statement in German added that the probe involved tournaments in the United States.

The Zurich Cantonal Police were questioning the detainees.

International media gathered at the street entrance of the Baur au Lac in scenes reminiscent of the World Cup votes won by Russia and Qatar more than four years ago.

Then, former President Bill Clinton was inside meeting FIFA voters who later rejected the American bid in favor of Qatar, and Britain's Prince William was part of the losing English bid team.

Suspicions of vote-buying and wrongdoing in those bidding contests have dogged FIFA ever since.

___

AP Sports Writer Rob Harris contributed to this report.