Several hundred people took part in an unauthorized nighttime demonstration in Bern, causing damage and traffic disruption.
Police say windows were smashed and graffiti sprayed on buildings, with losses estimated in the tens of thousands of francs.
The march began late Saturday evening and moved through the city centre before dispersing in the early hours. Participants set off fireworks and played loud music.
The reason for the march was unclear - protestors say they were against business plans by the city and police behaviour.
Authorities say the protest was not officially declared, though police escorted the procession and maintained security throughout.
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