Police in Basel have fired tear gas and rubber bullets to break up a crowd of about 400 anti-Turkish protestors, who were demonstrating against conditions in Turkish prisons.
The demonstration on Wednesday came a day after protesters battled with police in Zurich, and briefly occupied the Swiss parliament in Bern, on Tuesday.
The protest turned violent after security forces tried to block the unauthorised demonstration. The crowd, made up mainly of Kurds, reacted by throwing bicycles and other objects at the police.
Several vehicles were reportedly damaged during the clashes.
Police and protesters exchanged blows and tension remained high for about an hour before the situation was brought under control.
The protesters in Basel, Zurich and Bern are believed to be mainly Kurds of Turkish origin.
Kurds have been staging a series of international protests about prison conditions in Turkey and proposals to transfer prisoners from dormitories to small prison cells where they fear abuse by the authorities.
Police in Turkey stormed the country's prisons this week to put an end to protests by the inmates.
swissinfo with agencies