Convicted match-fixer Wilson Raj Perumal has denied he correctly predicted Cameroon’s result against Croatia to Der Spiegel magazine before the game.
Der Spiegel is standing by its report but has yet to provide definitive evidence of the Facebook discussion with a journalist.
Fifa’s head of media Delia Fischer said: “We have requested Der Spiegel to provide us with all the communications with Perumal and any other material in order to prove the allegations they have made.
“So far we have no evidence of any match manipulation on the betting market. The media and other stakeholders should not call people’s or organisation’s credibility into question just for headlines.
“It is really important to make sure that information is handled with the necessary respect and care.”
Der Spiegel had claimed Perumal correctly predicted Cameroon would lose 4-0 against Croatia and a player would be sent off.
Cameroon did indeed lose by that scoreline, with Alex Song dismissed in the first half.