Two Fifa vice-presidents have been arrested in a dawn raid at a Swiss hotel on suspicion of accepting millions of dollars of bribes.
Concacaf president Alfredo Hawit and Conmebol president Juan Angel Napout were taken from the Baur au Lac hotel, Zurich, where several Fifa officials were also arrested in May.
Fifa's executive committee has been meeting in the city, voting on reforms.
It says it will "fully co-operate" with separate US and Swiss investigations.
The US Department of Justice requested Thursday morning's arrests as part of its ongoing investigation into corruption in football's world governing body.
Hawit, 64, is interim president for North, Central America and Caribbean football, while Napout, 57, oversees football in the South American confederation.
They are alleged to have taken money for selling marketing rights in connection with football tournaments in Latin America, as well as World Cup qualifying matches, the Swiss Federal Office of Justice (FoJ) said.
"According to the US arrest requests, they are suspected of accepting bribes of millions of dollars," it said, adding the pair had opposed their extradition to the United States at a hearing earlier.
Fifa's reform committee chairman, Francois Carrard, said at a news conference in Zurich the arrests were "a very important step" as part of changes "so Fifa can renew itself".
Speaking after a raft of reforms were approved on Thursday, he added: "Fifa is going through a major crisis - a crisis is a unique opportunity for change, for renewal."
In May, seven Fifa officials, including another two vice-presidents, were arrested at the same Zurich hotel at the request of US authorities, as the governing body became engulfed by claims of widespread wrongdoing.
A Swiss criminal investigation into the bids for the 2018 and 2022 World Cups was also launched earlier this year, alongside the US inquiry.