Swiss prosecutors have opened a criminal investigation into FIFA President Sepp Blatter, according to media reports.
Blatter is being investigated "on suspicion of criminal mismanagement as well as – alternatively – on suspicion of misappropriation", the Swiss announced.
It said Mr Blatter was currently being questioned.
The Swiss attorney general's office said the investigation surrounds a TV rights deal Mr Blatter signed with Jack Warner in 2005.
Blatter is also suspected of "a disloyal payment" in 2011 to UEFA president Michel Platini, the statement said.
Fifa said it was co-operating with the Swiss attorney general and had complied with its requests for information.
"We will continue this level of co-operation throughout the investigation," it said.
Meanwhile, FIFA have confirmed that the 2022 World Cup in Qatar will be played from November 21 to December 18.
The tournament was widely expected to be scheduled for the winter months due to health concerns over the extreme heat in the summer, which is when the World Cup is traditionally played.
The decision to award the tournament to Qatar was met with controversy as Swiss and US authorities are currently investigating the bid in their probe into allegations of corruption.
Following a FIFA executive committee in Zurich on Friday, the dates of the 2022 World Cup were announced, with the final being held a week before Christmas on December 18, according to PA.
Meanwhile, outgoing FIFA president Sepp Blatter was due to address the media in a press conference following the committee meeting, but it was cancelled five minutes before it was due to begin.