Austrian police detained about 140 mostly German fans on Sunday as Germany launched their Euro 2008 campaign with a 2-0 win over arch-rivals Poland.
"Some 140 high risk fans were detained following dangerous attacks, administrative offences and the suspicion of having committed legal offences," a spokesman for Klagenfurt police said. "Most of them are German, though we are still in the process of checking everyone's identity."
Austrian police said in a statement that the fans had been watched for some time and had been detained in a joint operation between Austrian and German police.
Austrian news agency APA had reported that two different groups of Germans were marauding the streets in Klagenfurt's city centre, shouting anti-Polish chants, before being detained for disturbing the peace by Austrian and German police forces.
Earlier on Sunday, police warned that potentially violent German, Polish and Austrian fans were known to be in Klagenfurt and others were heading to the city.
Some 2,500 officers are on duty in Klagenfurt, Euro 2008's smallest host city, including 70 hooligan spotters.
German and Austrian police were highly visible in the city centre, standing at street corners close to drinking fans.
The incident recalls scenes in the German city of Dortmund during the 2006 World Cup, where police detained more than 400 people after outbreaks of violence in the run-up to the Germany-Poland match.
(Writing by Karin Strohecker, editing by Jon Bramley and Ken Ferris)