Berlin, Dec 4 (IANS): The wives and children of Islamic State (IS) terrorists returning to Germany may pose a security threat, the head of the country's domestic intelligence agency said.

Hans-Georg Maassen, in charge of the so-called Verfassungsschutz (Federal Office for the Protection of the Constitution), said that the large-scale loss of territory by IS terrorists in Syria and Iraq had led to the return of some of their families to Germany, Xinhua reported citing DPA news agency.

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

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

Of the 950 people who had left Germany for Syria and Iraq to fight on behalf of IS in recent years, roughly a third had returned, while many were believed to have died.