BERLIN (AP) — Germany’s domestic intelligence chief says more than 400 Islamic extremists from the country are now believed to have traveled to Syria, and about 25 have returned with experience of battle.

Hans-Georg Maassen told news agency dpa in comments published Thursday that authorities have “no indications that these people are pursuing a concrete terrorist mandate in Germany.”

However, authorities are alert to the risk posed by radicals returning from Syria’s civil war. A Frenchman who had fought in Syria is suspected of killing four people at Brussels’ Jewish Museum in May. Maassen says that shows the return of fighters from Syria “has developed into a European problem.”

In April, Maassen’s agency estimated the number of extremists from Germany who had gone to Syria since fighting broke out there at over 320.

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