UEFA insist they will only open an investigation into claims of corruption surrounding the appointment of Poland and Ukraine as Euro 2012 hosts if evidence is produced.
Spiros Marangos, treasurer of the Cyprus Football Association, made the allegations in German newspaper Suddeutsche Zeitung. UEFA said the claims are unsubstantiated and called for proof to be produced by Wednesday.
UEFA said in a statement:" UEFA has taken note of recent media reports according to which an individual from Cyprus claims to be in possession of evidence that certain UEFA representatives were corrupted in relation to the appointment of Poland and the Ukraine as hosts for UEFA EURO 2012. In relation to this as yet unsubstantiated claim UEFA wishes to state that, as always, it can only open an investigation on the basis of tangible elements of proof."
The statement continued: "To date these have never been provided to UEFA by this individual prior to any meeting and this in spite of repeated requests by Europe's governing football body.
"UEFA has therefore, via its legal counsel, again requested said individual to submit to UEFA any evidence that according to him should confirm his allegations, by Wednesday 27 October at the latest.
"If any such tangible elements are delivered, UEFA will then open the corresponding disciplinary case and will submit such evidence to the competent authorities."
The allegations are the latest claims to rock the world of football following the Sunday Times expose of two FIFA executive committee members who asked for money in return for World Cup votes.
UEFA said they were leaders in the fight against corruption and threatened legal action against unsubstantiated statements.
The European body added: "If no such evidence is submitted within the time frame, UEFA reserves its right to start legal proceedings, civil and criminal, against any individual or individuals making such defamatory statements.
"The fight against corruption is taken very seriously by UEFA which has taken, and continues to take, all necessary steps to sanction and eradicate it, but UEFA aims equally to protect integrity and truth by taking action based on facts and evidence alone."