FIFA investigator Michael Garcia Wednesday said he had prior access to the "vast majority" of documents revealed recently which allege millions of dollars in bribes helped Qatar secure the 2022 World Cup.
Garcia told the FIFA congress in Sao Paulo that he was prepared to use the documents printed by Britain's Sunday Times in his probe, shooting down media "assertions" that he may ignore them.
The explosive documents have cast new doubt on Qatar's World Cup, with major sponsors urging a thorough investigation and some FIFA delegates calling for a re-vote if corruption is proved.
"The vast majority of that material has been available to us for some time, since well before the recent wave of newspaper reports," Garcia said.
"That material has been and will continue to be examined and reviewed to the extent relevant to the investigation into the World Cup bidding process or any other investigation or inquiry."
The British newspaper has published a series of reports based on millions of leaked emails and documents which claim widespread bribery orchestrated by former Asian football chief Mohammed bin Hammam.
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Garcia said investigators had combed through the newspaper's reports and all the documents attached. He said they had gone to "what appears to be the original source" and should have access the entire cache of data.
The US lawyer completed his probe on Sunday but he is not due to submit his report to the adjudication chamber of FIFA's ethics committee for another six weeks.
"What we cannot do and what I will not do is postpone indefinitely our work on the possibility someone may publish something we may not have seen," he warned.
"No, we will follow our process, a process being considering the greatest number of allegations and issues in as thorough manner as possible."
The adjudication chamber is expected to announce its decision in September or October. It has powers to hand out sanctions, open a disciplinary procedure or decide there is no case to answer.
Garcia said investigators had interviewed members of all the bidding teams for the 2018 and 2022 World Cups and had reviewed tens of thousands of documents.
He added they had interviewed, or tried to interview, all members of FIFA's executive committee at the time of the 2010 vote.
Media reports have said German legend Franz Beckenbauer, an executive committee member at the time, is facing sanction for failing to cooperate with the investigation.