UEFA has given Mr Marangos two days to provide "tangible elements of proof".
"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," said a UEFA statement. "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 today, via its legal counsel, again requested the said individual to submit to UEFA any evidence that according to him should confirm his allegations, by Wednesday 27 October at the latest."
Lawyers for Marangos told the BBC that he had tried for the past two years to draw UEFA's attention to the allegations and that Marangos had been due to meet the head of UEFA's disciplinary committee in August but the meeting was cancelled by UEFA four days beforehand.
