Police in the German city of Hamburg are preparing for a potential security headache as leaders of the G20 gather on the July 7.
Authorities anticipate some 10,000 far-left activists will descend on Hamburg from across Europe.
Kurdish and Turkish activists are also expected adding to the volatile concoction.
Hamburg will deploy some 15,000 police officers for the summit with reinforcements due to arrive from other German regions
German Interior minister Thomas de Maiziere spoke to a gathering of police officers:“Peaceful protest is welcome and allowed in our democracy. Violent protest, however, cannot invoke the basic right of freedom to assemble as written in our constitution, and will be prevented.”
An additional 5,000 federal officers will also be on site to protect heads of state and government leaders and have been trained to deal with most eventualities.