The wives and children of Daesh terrorists returning to Germany may pose a security threat, the head of the country's domestic intelligence agency told German Press Agency (DPA) in an interview published Sunday.

Hans-Georg Maassen, in charge of the so-called Verfassungsschutz, said that the large-scale loss of territory by the Daesh terrorist group in Syria and Iraq had led to the return of some of their families to Germany.

"There are children who were subjected to brainwashing at 'schools' in [Daesh] territory that have been strongly radicalized," Maassen said. "For us, this represents a problem because these children can be dangerous."

He added that the wives of the terrorists are often similarly radicalized.

Of the 950 people who left Germany for Syria and Iraq to fight on behalf of Daesh in recent years, roughly a third have returned, while many are believed to have died. Germany is obliged to grant entry to those that hold German citizenship.