German Interior Minister Thomas de Maizier said Friday there were 2,000 Europeans fighting with the Islamic State in Iraq and Levant (ISIL).
"We are not talking about unorganized individuals as we have believed, we think their return to their countries is a matter of concern of the security authorities in the European countries," he said in a statement to the press.
Commenting on demands by some German parties to withdraw nationalities of the European fighters, de Maizier said stripping the Germans from their nationalities was very difficult because the government has no proof of their faith nor there were evidence of their involvement in terrorist acts.
Germany's intelligence service had said more than 400 Germans had travelled to Syria since 2011. Only 100 of them returned home.