NEW YORK (AFP) - Chuck Blazer, once the most powerful man in US football, was an FBI informant used to spy on Fifa, the New York Daily News reported.
Blazer, who is now suffering from cancer, secretly recorded conversations with officials he arranged to meet at his London hotel during the 2012 Olympics, the report said.
The US Federal Bureau of Investigation, or FBI, pressured Blazer into working for them from 2011 because he failed to pay income taxes on millions of dollars he made as a leader of Concacaf, football's governing body for North and Central America and the Caribbean, said the report published at the weekend.
Those he invited to the meetings in London included Russia's 2018 World Cup organising committee chief Alexei Sorokin and Frank Lowy, head of the Australian 2022 bid, but it is not known whether they actually met Blazer.
Blazer was the "whistle-blower" in the Caribbean vote-buying scandal that resulted in the resignation or expulsion of his longtime Concacaf colleague Jack Warner and Fifa vice-president Mohamed Hammam in 2011.
Blazer himself resigned from Fifa's executive committee in 2013 after a Concacaf audit found he had received millions of dollars in undeclared commissions.
The bidding process for the 2018 and 2022 World Cups has been the subject of a corruption probe headed by Michael Garcia, a former US prosecutor, who has tendered his report to Fifa .
Fifa has faced calls to release the report in full, but has said it could not do so for legal reasons.
An intense spotlight has been put on the report following allegations that Hammam, a former head of Qatari soccer, paid national federation chiefs millions of dollars to back Qatar, which won the right to host the 2022 World Cup in a controversial 2010 vote by the Fifa executive committee.
The Gulf state has denied any wrongdoing.