Speaking to German police chief Frank Rogatty, German Chancellor Merkel said Germany and its allies had achieved significant advances against "Islamic State" (IS) - pointing to the liberation of the Iraqi city of Mosul as an example.

"This in turn has raised the threat level in our country, because the aggressiveness has increased," the chancellor said.

The German leader's remarks came on Saturday during her weekly video podcast, just as Defense Minister Ursula von der Leyen visited Bahrain to discuss with allies ways to defeat the so-called "Islamic State" (IS).

Von der Leyen discussed IS during a security conference in Bahrain

'A coalition for education'

Merkel's warning was released the same day von der Leyen spoke at the Gulf security conference alongside her US and European counterparts. The German defense minister emphasized that IS could only be defeated once governments put more emphasis on spreading liberal values and creating economic opportunities for the sort of young people who travel abroad to join IS.

"We should complement the coalition against terror with a coalition for education," von der Leyen said.

"To win the war we have to dominate the internet," she added. "But to win peace we have to offer hope and a future."

French Defense Minister Jean-Yves Le Drian echoed von der Leyen's statement, arguing that military might alone would not defeat terrorism.

More Islamists in German jails

But while politicians debate which education measures will keep people from radicalizing, a new report showed a dramatic increase in the number of radical Islamists in German prisons.

According to a survey conducted by the country's Ministry of Justice and reported on in the daily "Rheinische Post," there are currently 150 Islamists in jail - an increase of about 30 percent over last year. Germany has experienced concerns over domestic terrorism following the country's intake of refugees from the Middle East and Central Asia.

blc/sms (AFP, epd)