FIFA announced they have opened an investigation into president Sepp Blatter on Friday as the corruption scandal gripping world football took another extraordinary twist.
Football's governing body said Blatter would appear before FIFA's ethics committee on Sunday after claims he knew about alleged cash payments at the centre of a corruption probe targeting his election rival Mohamed Bin Hammam.
Bin Hammam had demanded the corruption investigation be widened to include Blatter on Thursday as the two men prepare to contest a June 1 election for control of world football.
The announcement came two days after Bin Hammam, FIFA vice-president Jack Warner and two Caribbean Football Union officials were summoned to the ethics committee to answer corruption allegations.
Bin Hammam and Warner were targeted after Chuck Blazer, general secretary of regional footballing body CONCACAF, reported possible misdeeds during a May 10 and 11 meeting in Trinidad.
British media reports said Bin Hammam and Warner are accused of offering $40,000 cash gifts to national associations at the Trinidad conference in return for their votes in next week's presidential election.
FIFA's statement on Friday said Blatter had been summoned to appear before the ethics committee to answer claims that Warner had told him in advance of alleged payments made at the meeting.
The statement continued: "Subsequently, the FIFA Ethics Committee today opened a procedure against the FIFA President in compliance with art. 16 of the FIFA Code of Ethics."
"Joseph S. Blatter has been invited to take position by 28 May 2011, 11:00 CET and to attend a hearing by the FIFA Ethics Committee at the Home of FIFA (Zurich) on 29 May 2011."
Blatter issued only a brief statement on Friday following FIFA's announcement.
"I cannot comment on the proceedings that have been opened against me today. The facts will speak for themselves," the Swiss powerbroker said.
Blatter has denied suggestions from Bin Hammam that he had orchestrated the charges against the man seeking to unseat him, dismissing them as "ludicrous."
"I take no joy to see men who stood by my side for some two decades, suffer through public humiliation without having been convicted of any wrongdoing ...," Blatter wrote in his column on the respected InsideWorldFootball blog.
"To now assume that the present ordeal of my opponent were to fill me with some sort of perverse satisfaction or that this entire matter was somehow masterminded by me is ludicrous and completely reprehensible."
The civil war which has erupted within FIFA's echelons this week follows weeks of corruption allegations involving the organisation's officials.
FIFA opened a separate inquiry after accusations made in the British parliament regarding the bidding process for the 2018 and 2022 World Cups.
Former English Football Association chairman David Triesman told a committee he had witnessed "improper and unethical" behaviour by four FIFA voters - including Warner - while campaigning for England's failed 2018 World Cup bid.
On Monday, Qatar denied claims aired in the committee that it paid large bribes to secure its shock victory in the battle to host the 2022 tournament. Bin Hammam, who was instrumental in the bid, has also rejected the allegations.