Mohamed bin Hammam will face an ethics investigation just days before he is due to challenge Sepp Blatter for the FIFA presidency after a report from within the organisation's executive committee alleged possible bribery.
FIFA said Wednesday it had begun ethical proceedings against Bin Hammam, the Qatari head of the Asian Football Confederation, along with CONCACAF president Jack Warner and two officials.
All four have been summoned to appear before FIFA's ethics committee on Sunday, three days before the vote for the most powerful job in world soccer, in response to a report from Chuck Blazer, CONCACAF's general secretary.
FIFA said Blazer's report, which included "bribery allegations", referred to a Caribbean Football Union (CFU) meeting which was attended by Warner and Bin Hammam on May 10-11 and was linked to the election campaign.
Bin Hammam strongly denied any wrongdoing and said he was confident he would still be allowed to stand in the June 1 vote, when he is the only challenger to Blatter.
"This has been a difficult and painful day for me today," Bin Hammam said in a statement. "But, if there is even the slightest justice in the world, these allegations will vanish in the wind.
“This move is little more than a tactic being used by those who have no confidence in their own ability to emerge successfully from the FIFA presidential election. Here I completely deny any allegations of wrongdoing either intentionally or unknowingly while I was in the Caribbean.
"I am confident that there is no charge to answer and that I will be free to stand in the FIFA presidential election on June 1 as originally planned."
Unlike last year's scandal, in which two executive committee members were banned following investigations by the Sunday Times newspaper, the allegations came from within FIFA for the first time.
CONCACAF, the North and Central America and Caribbean Confederation, holds 35 of the 208 votes at the FIFA Congress which will choose between Bin Hamman and incumbent President Blatter.
Warner has always been regarded as a staunch Blatter supporter but said his confederation had not yet chosen who it would back this time.
FIFA would not comment on whether the election might now be postponed.