“There are plans to introduce a legal amendment, for Germans with multiple 
nationalities who fight for a terror militia, to lose their German citizenship,” said interior ministry spokeswoman Eleonore Petermann. 

Justice Minister Katarina Barley has separately said that the change would be “implemented soon”, her spokeswoman said.

Under German law, individuals with more than one nationality can already lose their German citizenship if they fight for a foreign army without permission from the German defence ministry.

The amendment would therefore add participation in combat for a foreign militant group to the existing law.

The new rule would also only apply under strict conditions — the individual must be above 18 years of age, and have more than one nationality, so that he or she would not be left stateless after losing the German citizenship.

The legal change will not apply retroactively, meaning that German IS fighters who are already jailed will not be affected.

Chancellor Angela Merkel's spokesman Steffen Seibert rejected claims that 
the amendment would leave dual nationals feeling like “second-class citizens”.

“We must not forget what this is about,” he said.

“This is about concrete participation in combat operations for a terror militia abroad,” he said. Merkel's government had committed to examining such an amendment during their coalition negotiations last year, he noted.

With the Islamic State organisation crumbling, many European countries are  now being confronted with the urgent question of what to do with returning 
fighters.

Britain recently sparked uproar when it decided to strip a teenage girl of her nationality, arguing that she could obtain Bangladeshi citizenship through her mother, a claim the government in Dhaka has rejected.