Bin Hammam has been accused of paying voters during a campaign visit to the Caribbean in a scandal that has also implicated FIFA Vice President Jack Warner, who was summoned by the same ethics panel.

Blatter also answered allegations that he turned a blind eye to the payment of bribes in the gravest corruption crisis of his 13-year reign, which has seen FIFA's reputation tarnished by repeated allegations of vote-buying and financial wrongdoing.

Franz Beckenbauer, who retires as a member of FIFA's executive committee next week, on Sunday described the crisis as a “disaster for football.” “I hope when June 1 comes and the election will be over, then all the discussion about corruption is finished and FIFA can go back to normal,” Beckenbauer told the BBC. “I don't know what's going on in the next days, but in general it's my opinion it's very, very bad.” If cleared, Blatter could get an unopposed run at a final four-year term at Wednesday's election.

But Warner, the CONCACAF President, has warned that a “football tsunami” would be unleashed after the findings of the FIFA panel are released, threatening the sport's governing body.

At the end of an astonishing week at FIFA's palatial slate and glass headquarters in Zurich, at 6 p.m. local time (1600 GMT) Sunday the ethics committee is scheduled to deliver initial findings that could lead to suspensions for the accused officials.

Bin Hammam, the head of Asian football, and Warner deny wrongdoing in relation to the meeting in Trinidad three weeks ago.

They have suggested a plot by Blatter supporters, but declined to respond to reporters' questions about the alleged bribes either before or after appearing before the ethics panel, which can suspend them from football duties.

The corruption crisis was sparked by American official Chuck Blazer, whose evidence file implicated his FIFA executive committee colleagues bin Hammam and Warner.

Blazer, Warner's longtime No. 2 at the CONCACAF regional body, spent more than an hour at FIFA headquarters before leaving.

Bin Hammam, who ran for the presidency after helping Qatar secure hosting rights for the 2022 World Cup, announced his withdrawal early Sunday morning “Recent events have left me hurt and disappointed - on a professional and personal level,” bin Hammam wrote on his personal website. “It saddens me that standing up for the causes that I believed in has come at a great price - the degradation of FIFA's reputation. This is not what I had in mind for FIFA and this is unacceptable.

“I cannot allow the name that I loved to be dragged more and more in the mud because of competition between two individuals. The game itself and the people who love it around the world must come first. It is for this reason that I announce my withdrawal from the presidential election.

“I pray that my withdrawal will not be tied to the investigation held by the FIFA ethics committee as I will appear before the ethics committee to clear my name from the baseless allegations that have been made against me.” The ethics probe opened days of scheduled meetings involving FIFA's 208 national members before their annual Congress on Wednesday.

Blazer delivered a file containing sworn statements from some Caribbean football leaders that sparked an explosive round of allegations, denials and conspiracy accusations in the final days of campaigning.

Blatter, bin Hammam and Warner passed up invitations to attend the year's most eagerly anticipated match on Saturday, the Champions League final between Barcelona and Manchester United in London, to focus on their legal defense.

Qatari challenger bin Hammam and Warner, a 28-year veteran at FIFA's high table, are accused of arranging bribes for up to 25 presidential voters on a campaign visit.

Caribbean Football Union members were allegedly offered $40,000 each at a May 9-10 conference in Trinidad, where Warner is a government minister.

Bin Hammam has acknowledged paying travel and accommodation expenses, and conference costs, but denies vote-buying.

Instead, he implicated Blatter's camp in a plot to remove him from the election contest, and fought back by successfully bringing the FIFA president into the ethics case.

According to bin Hammam's formal complaint, Blatter broke FIFA “duty of disclosure” rules because he was apparently aware via Warner that payments had been arranged and “had no issue.” Warner dismissed suggestions that the evidence file compiled by John Collins, a former United States federal prosecutor who is now a member of FIFA's legal committee, could end his career within football's ruling body.

Two Caribbean Football Union staffers from Trinidad, Debbie Minguell and Jason Sylvester, have also been summoned to the FIFA ethics hearing.

Namibian judge Petrus Damaseb headed the hearing after Swiss ethics committee chairman Claudio Sulser removed himself because he shares nationality with Blatter.

American member Burton Haimes also stepped aside because of long-standing links with Warner and Blazer.

After the election, Blatter has promised to tackle allegations of past corruption and strengthen FIFA's panels that investigate alleged wrongdoing.

Blatter succeeded Brazil's Joao Havelange, defeating then UEFA president Lennart Johansson at the 1998 FIFA Congress.

Blatter acknowledges that claims of vote-buying surrounded his first election but has always denied involvement.

After facing a challenge from African football president Issa Hayatou in 2002, Blatter was re-elected unopposed for a third successive term in 2007.