UEFA President Michel Platini is seen during the draw ceremony for the 2014/2015 Champions League soccer competition in this picture taken August 28, 2014 at Monaco's Grimaldi Forum in Monte Carlo. [Photo/Agencies]

FIFA will elect a replacement for Blatter on Feb. 26. Platini, who has registered as a candidate, cannot run while he is banned, but might be allowed to take part if he is cleared.

Even a temporary reprieve from the CAS could open the door for Platini, although FIFA's electoral commission said it would study the case depending on the timing.

However, FIFA's ethics committee is due to make its final decision on the case, which could include bans of several years or more, by Christmas.

Earlier, on arriving, Platini said he would tell the panel "the truth, all the truth and nothing else but the truth. I swear it."

The investigation centres on a 2 million Swiss franc ($2 million) payment from FIFA to Platini, a former France team captain and coach who has been UEFA president since 2002, in 2011 for work he completed between 1998 and 2002.

Both Blatter and Platini have denied wrongdoing.