Germany’s domestic spy agency, the Federal Office for the Protection of the Constitution (BfV), has warned that the children of jihadists who travelled to the Middle East and are now returning could pose serious security risks and become a “new generation” of Islamic radicals.

Head of the BfV Hans-Georg Maaßen made the warning this week, saying: “We see the danger that children of jihadists are Islamically socialized and return from the fighting areas to Germany indoctrinated.”

Maaßen added that the Islamic State had taken great care to fully brainwash young children to make them as deadly and ruthless as possible, Kronen Zeitung reports.

“In Islamic State propaganda, children stand for a new generation of IS fighters who are portrayed as unscrupulous and brutal,” Maaßen said.

Due to the ever increasing losses in territory for the Islamic State in both Iraq and Syria, the BfV believes that many of the Islamic radicals who left Germany to fight for the terror group will soon start to return in large numbers.

Around 950 radical Islamists have departed from Germany to fight for the terror organisation and so far only around a third of them have returned to Germany. Among the 950, five percent are believed to be minors.

Sikh Temple Bombing May Have Been Directed By Salafist Group https://t.co/S6tz3jW7Lr pic.twitter.com/36QDjw4Zzl — Breitbart London (@BreitbartLondon) June 1, 2016

Maaßen also noted the growing number of radical Islamic Salafists in Germany, who would likely aid the returning fighters from the Middle East. Recent reports have claimed there are upwards of 10,000 Salafists in the country, with around 1,800 considered to be violent extremists.

The problem is not limited to Germany, as many other countries across Europe have seen hundreds of their citizens travel to fight for the Islamic State, some taking their entire families with them. One such radical was Swedish Muslim convert Michael Skråmos.

Skråmos, a former “Islamophobia” expert, joined the Islamic State in 2015, and has been seen in their propaganda videos. Most recently the Swedish jihadi called on IS supporters in Sweden to commit acts of terrorism in the country.