Addressing delegates at FIFA's annual Congress in Switzerland, where members will later vote to decide the organisation's presidency, Blatter promised more transparency and urged members to remain unified.

Europe, which accounts for all but three of the countries that have ever made it to a World Cup's final match, is particularly keen to banish the 79-year-old Swiss. But Asian, African and Latin American states are expected to rally around him. Each of the 209 countries in FIFA has an equal vote.

On a visit to Berlin, British Prime Minister David Cameron told Blatter to go "the sooner the better". Chancellor Angela Merkel said the dirty side of soccer must be cleaned up. In a low key-address that contrasted with a more defiant reaction on Thursday, Blatter said he was "appealing to unity and team spirit so we can move forward together."

He also sought to distance himself from the scandal, the biggest crisis FIFA has faced in its 111-year history. U.S. authorities have accused top FIFA figures and sports executives of corruption, while Switzerland is investigating the award of the next World Cup finals to Russia and Qatar.

The scandal widened on Friday when Britain's Serious Fraud Office said it was examining possible corruption at FIFA. A judge in Argentina has ordered the arrest of three businessmen accused of using bribery to obtain soccer media rights, and the Brazilian Senate moved to open a formal inquiry into soccer bribery allegations.

FIFA takes in billions of dollars in revenue from television marketing rights and sponsorships, making it one of the wealthiest and most powerful sports bodies in the world. It has been dogged by corruption scandals for decades, mostly investigating itself and avoiding scrutiny by criminal courts.

"We cannot watch everyone all the time. We have 1.6 billion people directly or indirectly touched by our game," Blatter said. Russia and Qatar deny wrongdoing in their successful bids to host the cup. Russian President Vladimir Putin has accused the United States of meddling in an effort to prevent Blatter's re-election.

Qatar on Friday issued a further defence of its bid and said it would carry on with plans to stage the event. The decision to host the world's biggest soccer tournament in a small desert state where daytime summer temperatures rarely fall below 40 degrees Celsius startled many in global sport.

Blatter, who has been criticised for not doing enough to combat corruption in FIFA, is being challenged by Jordanian Prince Ali bin Al Hussein for the most powerful job in soccer.

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