Sepp Blatter says FIFA will interview a whistleblower at the centre of newspaper allegations that Qatar paid two members of the executive committee to vote for their bid to host the 2022 World Cup.
The FIFA president, bidding to be re-elected for a fourth term on June 1, also refused to rule out the possibility of re-staging the vote, won by Qatar, should the allegations turn out to be true.
Last week, a British parliamentary inquiry into England's failed bid to host the 2018 finals was told by a member of parliament there was evidence from the Sunday Times newspaper that Issa Hayatou of Cameroon and Jacques Anouma of the Ivory Coast were paid by Qatar.
Blatter, who stands for re-election against Asian football chief Mohamed Bin Hammam at the Congress, says FIFA wants the matter clarified by the end of next week.