FIFA has placed secretary general Jerome Valcke on leave and released him from his duties with immediate effect.
Reports emerged on Thursday linking Valcke to a scheme that intended to sell tickets for the 2014 World Cup in Brazil at above their face value, but the contract was cancelled before any were sold.
Valcke – the right-hand man to FIFA president Sepp Blatter since 2007 – denies the allegations, which were made by former footballer and tickets and hospitality consultant Benny Alon.
The claims are said to relate to a contract between JB Sports Marketing, a company for which Alon worked, and FIFA for Brazil 2014 ticket and hospitality packages.
A statement released by FIFA confirmed that it had requested a formal investigation into the allegations by its Ethics Committee.
The statement read: "FIFA today announced that its Secretary General Jerome Valcke has been put on leave and released from his duties effective immediately until further notice.
"Further, FIFA has been made aware of a series of allegations involving the Secretary General and has requested a formal investigation by the FIFA Ethics Committee."