The federal police and Germany's domestic intelligence agency, the Federal Office for the Protection of the Constitution, found in a joint study that a smaller number of "Islamic State" (IS) supporters were traveling to Syria and Iraq.

Klaus Bouillon, head of the Conference of Ministers of the Interior, told the German dpa news agency that nearly 100 supporters were traveling to IS war zones during "peak times." That number had dropped down to less than five a month more recently.

IS was recruiting potential supporters via the internet and among Salafist groups, Bouillon said. Meetings on Islam and activities involving the distribution of the Koran were also used to pick up sympathizers, he added.

But German authorities were employing effective strategies to combat the crisis, Bouillon's colleague Joachim Hermann, interior minister of Bavaria, told dpa news agency.

"Over two years ago, we agreed we would prevent people planning to travel to civil war regions in Syria and Iraq from leaving the country," Hermann said, adding that German state interior ministers had done so and that officials seized passports and identity documents of these potential supporters.

But despite the decreasing numbers, individuals are still trying to join IS in Iraq and Syria, Hermann said. He also said that officials wished for more cooperation with mosques in Germany, adding that many Muslim communities did not have any affinity towards IS or terrorism.

"The majority of mosques are peaceful," he said. However, there were several Islamist groups that were problematic from the point of view of domestic security. The state has a clear expectation that these communities will cooperate with security officials, he said, adding that "some did, but others promoted radical opinions."