About 100 Germans have died fighting within the ranks of the Islamic State in Iraq and the Levant (ISIL) since 2012, according to the country's interior minister.

In comments published Sunday, Thomas de Maziere said that about 700 had travelled to Syria and Iraq to fight alongside ISIL in the last three years.

About a third of those who travelled to the region to fight have since returned, de Maziere told Germany's Bild am Sonntag newspaper.

De Maziere said Germany has blocked travel to the region in an effort to control the problem.

There are currently almost 600 investigations into 800 individuals on allegations of illegally travelling to the region to fight, he told the newspaper.

The minister also pointed to recent changes in German law that give authorities the right to confiscate identity papers from anyone seeking to travel to a Middle Eastern war zones.

The DPA news agency said that the law bans a person from leaving Germany for three years and makes it easier to press charges against anyone who attempts to travel to the region to participate in "terrorism activities".

Other changes to German law have made it easier for authorities to crack down on the financing of terrorism.

Earlier this month, Hans-Georg Maassen, the head of Germany's domestic intelligence, said that fewer Germans went to Syria and Iraq to fight with ISIL in the past few months than during last year's surge following the group's declaration of a 'caliphate'.

"We expect that the numbers will continue to increase, probably not as dramatically as we experienced last year, but ISIL, Syria and Iraq and this battlefield are still attractive for young people from Germany who want to become jihadists," Maassen told the Reuters news agency.

Early in August, ISIL released a video of some of its fighters speaking in German calling on Muslims in Europe to join the ranks of the group.

The Syrian Observatory for Human Rights said last month that more than 37,000 foreign fighters have died during the ongoing conflict in Syria.