UEFA have given police a list of 15 matches they suspect may have been fixed, a senior UEFA source said.
News of the match-fixing investigation came as UEFA officials and coaches gathered in Lucerne ahead of Sunday's draw for Euro 2008, to be played in Switzerland and Austria.
According the source, who spoke to Reuters on condition of anonymity, "15 matches are under investigation and being dealt with by UEFA's disciplinary committee."
The matches under suspicion were played in a variety of UEFA competitions including a Euro 2008 qualifier, Champions League qualifiers, UEFA Cup qualifiers and UEFA Cup and Intertoto Cup ties.
UEFA would not confirm when the matches took place although a 96-page dossier handed to Interpol last month goes back to July 2005.
Irregular betting patterns on the matches alerted UEFA to the possibility that some may have been fixed.
Graham Bean, an ex-police officer and former head of the English FA's Compliance Unit, said the affair could become the biggest of its kind to hit the international game.
Bean told the BBC World Service on Saturday: "These are clearly exceptionally serious allegations, but having said that they will be extremely difficult to investigate.
"Clearly for UEFA to pass this report across (to the police) they must have evidence of some kind, perhaps as a result of betting patterns, or individuals telling them what they know.
"If they can prove it then any punishments involved should be excessive. For something of this magnitude involving these type of games like Euro 2008 qualifiers and Champions League matches, then this is potentially one of the most serious things that has ever happened in world football."
Earlier this week, UEFA opened an investigation into the Intertoto Cup match between Bulgarians Cherno More and Macedonia's Makedonija on July 7, which Cherno More won 4-0.
The Bulgarian club have strongly denied any wrongdoing.
"It's an extremely unpleasant case but we think that the charges are unwarranted," Cherno More's lawyer Mihail Statev said at a news conference.