Fifa says there has been no evidence of match-fixing at any World Cup match and has called on a German magazine making allegations to provide proof.
Convicted match-fixer Wilson Raj Perumal has denied he correctly predicted Cameroon's result against Croatia before the game.
Der Spiegel magazine, which made the allegations, is standing by its report.
Fifa's head of media Delia Fischer said: "So far we have no evidence of any match manipulation."
She added: "We have requested Der Spiegel provide us with all the communications with Perumal and any other material in order to prove the allegations they have made."
Cameroon lost each of their three Group A games, including a 4-0 defeat by Croatia in which midfielder Alex Song was sent off in the 40th minute.
The Croatian FA says it did not have any concerns "during or after the match". A spokesman added: "We feel like we won that match on the field and at this moment it will stay at that."
Asked if he had seen any evidence or had suspicions of match-fixing at the World Cup, former Liverpool manager Gerard Houllier - a member of Fifa's technical support group - said: "No, not at all."