At least three Champions League games and 12 Europa League matches are under suspicion, prosecutors said. The matches are believed to have been played this year.

"We at UEFA are stunned by the magnitude of this," the European governing body representative Peter Limacher said in a Bochum police news conference.

"This is undoubtedly the biggest match-fixing scandal that European football has ever seen. Now we must do everything to make sure those referees, players and officials are taken to justice."

Police said it conducted more than 50 raids in Germany, Britain, Austria and Switzerland on Thursday. It made 17 arrests in process.

"UEFA will be demanding the harshest of sanctions before the competent courts for any individuals, clubs or officials who are implicated in this malpractice, be it under state or sports jurisdiction," UEFA general secretary Gianni Infantino said in a statement.

UEFA's betting fraud detection system, which they introduced following match-fixing scandals in Italy and Germany, has seemingly proved to be effective.

In 2006, Italian giants Juventus were relegated to the second division for their role in a match-fixing scandal.

Fiorentina, AC Milan and Lazio, who were also found guilty, had points deducted.

One year earlier, German referee Robert Hoyzer revealed that he tried to manipulate games in the second division, third division and German Cup.