Michel Platini's lawyer wants the UEFA president to be exonerated of any financial malpractice after a French newspaper said it had uncovered evidence he was assigned to carry out paid work for FIFA around the turn of the century.
Platini has been provisionally suspended from his role as a FIFA vice-president while an investigation takes place into a ?1.3million payment he received from FIFA in 2011.
The former France international has said it was payment for serving as technical adviser to FIFA president Sepp Blatter between 1999 and 2002 - long before Platini became UEFA president - which could not be paid at the time due to FIFA's financial situation.
Platini has insisted everything about the payment - which was made three months before a FIFA presidential election in which Platini opted not to challenge Blatter - was above board and properly handled.
The Journal du Dimanche newspaper said it had obtained a document dating back to November 12 1998 and distributed to members of UEFA's executive committee in which it is written that "we hear about a salary of one million Swiss francs" for Platini to take on an advisory role with FIFA.
Platini's lawyer, Thibaud d'Ales, told the newspaper: "This document just shows, contrary to the argument on which this accusation rests, that Michel Platini's contract with FIFA had no mysterious nature, and numerous people, including UEFA and FIFA, knew about it since 1998."
Platini, whose campaign to become the next FIFA president has been derailed, has repeatedly stressed the arrangement he had to work for Blatter was an oral contract.
The 2011 payment was signed off by Blatter, who is also currently suspended from office by FIFA.
In September, Swiss prosecutors opened criminal proceedings against Blatter and questioned Platini.
The Swiss attorney general's investigation included the allegation that the money paid by FIFA to Platini was " a disloyal payment" - contending it did not serve the best interests of world football's governing body.
Blatter has also denied any wrongdoing.