FIFA investigator Michael Garcia has seen most of the documents which form the basis of recent corruption allegations.
US attorney Garcia is leading the investigation into allegations of corruption in the bidding process to secure the right to host the 2018 and 2022 World Cups.
Garcia said he has received information from a number of sources including a whistleblower hotline, the media, football officials and private citizens.
Garcia told the FIFA Congress in Sao Paolo: "Recently there have been assertions about what material I will or will not consider.
"No one should assume what information we have or do not have - we have reviewed the documents and the vast majority has been available to us for some time, well before the recent wave of news report.
"These will continue to be examined and reviewed and we have gone to what appears to be the original source of that data and are confident we will have full access to that before issuing any final report.
"What we cannot and will not do is postpone indefinitely completing our work because someone, somewhere will publish something else.
"It is a process we believe will deliver a report that is comprehensive and fair to all parties."
Garcia also issued a veiled threat to officials such as Franz Beckenbauer, who refused to co-operate with the investigation into the bidding for the 2018 and 2022 World Cups, that they could face heavy sanctions.
He said: "The FIFA code of ethics requires all football officials - essentially everyone who has the privilege of working in football – to co-operate with ethics committee investigations and it makes real penalties available against those who fail to fulfil this obligation."
FIFA football committee member Beckenbauer told German media he did not respond to Garcia's interview request because he did not understand all of the questions sent to him in English.
He said: "Therefore I politely requested a meeting in which we could talk about the matter in German. That was apparently not desired. That aside, I wouldn't be able to contribute anything to clear up the matter anyway."