FIFA insisted Thursday they were "committed" to working with the authorities in any investigation, following the suspension of secretary general Jerome Valcke.
Swiss prosecutor Michael Lauber has requested to have access to all Valcke's emails while working at football's governing body.
"We are committed to collaborate with the authorities," FIFA told AFP without giving details because the case "is an ongoing process."
Valcke was put on indefinite leave last week over accusations he agreed to let World Cup tickets be sold at vastly inflated prices. The Frenchman strongly denied the allegations.
The claims were made by Benny Alon, an American-Israeli consultant at a company which had a deal with FIFA to sell tickets at the 2014 World Cup. The contract was subsequently cancelled.
His eviction has only served to heighten the suspicion which is swirling around president Sepp Blatter's final months in office with the election of his successor set for February 26 next year.
From corruption investigations in the United States and Switzerland to the sudden suspension of his right-hand man, Blatter can expect a barrage of questions when he faces the media on Friday.
Blatter's press conference, his first appearance since the Valcke's removal, will follow a two-day FIFA executive committee meeting which gets underway on Thursday in Zurich.
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