Two criminal probes into corruption at football's governing body Fifa are under way, after seven senior officials were arrested in Zurich on US charges.
Separately, Swiss prosecutors launched a criminal case into the bids for the 2018 and 2022 World Cups, to be held in Russia and Qatar respectively.
Nine football officials are among 14 people indicted on corruption charges, the US justice department says.
Fifa plans to go ahead with elections for its next president on Friday.
Incumbent President Sepp Blatter is seeking a fifth term. He was not one of those arrested.
Prince Ali Bin al-Hussein of Jordan — Mr Blatter's rival for the Fifa presidency — described the arrests as "a sad day for football".
Fifa's Zurich headquarters has also been raided, with electronic data and documents seized.
'Rampant, systematic, deep-rooted'
The US justice department said 14 individuals were under investigation worldwide, including high-ranking Fifa officials, for allegedly accepting bribes worth $150m (£97m). They include:
"The indictment alleges corruption that is rampant, systemic, and deep-rooted both abroad and here in the United States," said US Attorney General Loretta Lynch.
Several officials have already pleaded guilty, the US Department of Justice says. These include Charles Blazer, the former head of Concacaf, who was previously on the Fifa executive committee.
Mr Blazer, one of Fifa's most senior US representatives, allegedly started working with the US Federal Bureau of Investigation (FBI) and took part in undercover work, according to US media reports.
Many have wondered how Sepp Blatter can have been in charge of Fifa for so long, amid so many reports of corruption, and yet remain, apparently, untouched.
One Swiss newspaper jokingly called him "the dark prince of football, the godfather, Don Blatterone' — but no inquiry has ever revealed proof of his involvement in bribery.
"He's a survivor," says one member of parliament, Roland Buechel. "Nothing ever sticks to him; there is always someone between him and the bribes."
Some old friends describe Mr Blatter as down to earth and open. Others who have worked with him say he is a man who resents opposition, pointing to the swift departure of Fifa colleagues who dared to question him.
What emerges, finally, is a man who both critics and supporters say cannot imagine his life without Fifa, a man whose tenure as president has outlasted three marriages.
But as scandal follows scandal, Mr Blatter's determination not to leave his post willingly could see him bundled unceremoniously out the back door.
Fifa "welcomes the process and cooperates fully with the attorney general of Switzerland," spokesman Walter DeGregorio told reporters on Wednesday.
"It is certainly a difficult moment for us," he added.
The Swiss Federal Office of Justice (FOJ) said that US authorities suspected the indicted officials of receiving $150m worth of bribes since the early 1990s for football tournaments in Latin America.
The crimes were agreed to and prepared in the US via US bank accounts, it adds.
Swiss authorities can immediately approve the extradition, the statement continues.
In a separate move, prosecutors opened criminal proceedings "against persons unknown on suspicion of criminal mismanagement and of money laundering in connection with the allocation of the 2018 and 2022 football World Cups," said a statement from the Swiss attorney-general.
Fifa has been mired in controversy in recent years, with the most recent allegations of bribery related to the 2018 and 2022 bidding process that awarded the World Cup to Russia and Qatar respectively.