Soccer's European governing body is investigating 40 cases of match-fixing involving Champions League and UEFA Cup matches.
Peter Limacher, head of disciplinary services at UEFA, told The Associated Press on Friday the cases involved early qualifying matches of clubs "mainly from eastern Europe" over the last four years.
"Right now it's mainly eastern Europe clubs being investigated. They know they are not going to be involved later in the tournament and they are going out, so decide, 'Let's make a profit," Limacher said. "In the cases we have seen, it's really the deliberate planned fix of the games, the whole games. First the result at halftime, then after 90 minutes.
"It might take some time (to convict) but, in cases where we can work together with the police, that might be possible."
Limacher said UEFA is building a network of informers across Europe to clamp down on match fixing.
UEFA announced last month that three Macedonian clubs were being investigated after banning the former champion FK Pobeda from European competitions for eight years.
One of the fixtures under suspicion is FK Milano's 12-2 aggregate loss in July against Croatia's Slaven Koprivnika in the second qualifying round of the Europa League, the new format for the UEFA Cup.