The FBI's investigation into allegations of corruption at Fifa includes scrutiny into the body's decision to award the 2018 and 2022 World Cups to Russia and Qatar, according to a US law enforcement official.
The official said the inquiry was looking "beyond" the recent claims made against a number of senior Fifa workers, including the leadership of outgoing president Sepp Blatter, who announced his resignation yesterday.
Meanwhile, Fifa secretary general Jerome Valcke - who has been implicated in a letter - said he does not understand the accusations against him.
He said he sees no reason why he should not remain in the post, adding: "I don't feel guilty".
Ex-Fifa vice president Jack Warner has vowed to release an "avalanche" of secrets in an extraordinary television address in Trinidad.
A full transcript of the confession of shamed Fifa official Charles 'Chuck' Blazer has tonight been released by the US justice department.
A Fifa whisleblower has described Sepp Blatter as a 'diabolical genius' - but said Russia and Qatar should keep their World Cups.