German authorities have banned all activity on behalf of the Islamic State extremist group, including the distribution of propaganda material and the display of its symbols, AP reported.
The decree issued Friday closes a legal gap that made it difficult to prosecute Islamic State supporters in Germany.
Interior Minister Thomas de Maiziere said in a statement the group represents a "threat to public security in Germany" and its recruitment efforts need to be stopped. Security agencies estimate at least 400 people from Germany have joined the Islamic State group and similar organizations.
The Westdeutsche Allgemeine Zeitung newspaper reported this week that a German citizen identified only as Silvio K. had published a video threatening attacks against Germany because of the country's support for Kurds fighting the Islamic State group.