The surveillance operation in North Rhine-Westphalia was revealed when the Westfalen-Blatt newspaper reported that a man who discovered he had been under observation complained that his rights were being violated.

A court in Muenster rejected the man's request, arguing that the interests of state security outweighed the rights of the plaintiff during the soccer tournament.

Court spokeswoman Gudrun Dahme confirmed the newspaper report.

North Rhine-Westphalia is the country's most populous state and host to three stadiums being used for World Cup matches _ in Cologne, Dortmund and Gelsenkirchen.

State interior ministry spokesman Wolfgang Beus said the surveillance was part of overall heightened vigilance aimed "not only, but also at known Islamists."

He would not say how many people are under observation.