German Chancellor Angela Merkel warned protesters against the use of violence ahead of next month's Group of Eight summit.
Merkel's government has stressed it welcomes peaceful demonstrations during the June 6-8 meeting of G-8 leaders to be held in the Baltic sea resort of Heiligendamm, but launched a series of security measures aimed a cracking down on radical anti-globalization protesters.
"One thing must be clear: Violence is no means for achieving political goals," Merkel said in her weekly podcast on Saturday. "I call on all those who support a humane version of globalization to do their part to ensure that protests are peaceful."
Earlier this month, police raided 40 offices and apartments used by left-wing protesters in Berlin, Hamburg and elsewhere, provoking protests.