BERLIN (AP) — Hamburg police say authorities in Italy, Spain, France and Switzerland are conducting raids as part of an investigation into the riots that accompanied last year’s Group of 20 summit in the German city.

Police gave few details of the raids that started early Tuesday. They said that, in France, authorities are looking for a male suspect in the riots for whom a European arrest warrant has been issued.

Hamburg saw three nights of violence during anti-globalization protests as the leaders of the world’s 20 biggest industrial and developing countries met in the port city in July.