Dutch police launched a high-tech hunt for fans banned from soccer games with a new computer technology.
The computer is programmed to call random fans at home during soccer games, identifying them by their voice, the public prosecutor's office said in a statement on Thursday. The calls cannot be redirected to mobile phones.
The new scheme also means that fans with stadium bans do not need to report to police in person during soccer games.
"We're trying out the new system this season, it's a pilot program," Justice Ministry spokeswoman Michaela Dupont said.
Dutch police are becoming known for using unorthodox methods to tackle soccer-related violence.
On Wednesday, they sent 17,000 text messages to the mobile phones of fans who attended a soccer match between rival clubs Feyenoord and Ajax last season, looking for clues about people who started riots in which 47 police officers and an unknown number of fans were injured.
Phone companies voluntarily handed over the mobile phone numbers of people who were in or around Feyenoord's Kuip stadium on the day of the match _ traceable using broadcasting masts in the area.
The phone companies did not give individual names to police, and police sent a standard message asking people to come forward if they had information.
But some suspects apparently thought they had been fingered. Four suspects contacted police Wednesday, and a fifth turned himself in directly.
Rotterdam police also filmed the clashes, and have posted images of suspects on their Web site.
Police say the images have led directly or indirectly to 100 additional arrests in the months after the game, the AP reports.