BERLIN (AP) — Germany’s justice minister is calling for a better exchange of information on violent extremists in the European Union following the riots that accompanied the Group of 20 summit.

Hamburg saw three nights of violence amid anti-globalization protests as leaders of the world’s biggest economic powers met, the worst of it on Friday. Police arrested 186 and temporarily detained another 225 people.

Justice Minister Heiko Maas said Monday that “the brutal riot tourists stop at no borders. A high proportion of the violent extremists traveled to the G-20 from other European countries.”

He added that “we experienced a new quality of violence, which we should react to with more cooperation in combating extremists.”

Hamburg’s city government, which oversaw the police operation at the G-20, is led by Maas’ center-left Social Democrats.