No-one was detained Tuesday but police said they were searching for documents, computer hard drives and other potential evidence in the 13 locations, mostly apartments, in Berlin, the neighbouring city of Potsdam and the eastern state of Thuringia.
The sweeping pre-dawn raids targeted the homes of members of the Koranic school of one of the men arrested Friday, Turkish-born Ismet D., 41, dubbed by media the “Emir of Moabit” after the Berlin district where the school is located.
The man, whose surname was not released under German privacy rules, is suspected of “leading an Islamist extremist group” made up of Turkish and Russian nationals from the Caucasus regions of Chechnya and Dagestan, police said last week.
There was no suggestion the two men or their supporters had planned any attacks against targets within Germany, said Berlin police spokesman Stefan Redlich.
“But we allege that they are supporting extremists in Syria,” he told private news channel NTV.
“We see a danger when people travel there, join the fighting, undergo military training and experience violence. We have to worry about these people when they return.”
Asked whether police had been more active against Islamists since the Paris jihadist attacks, he said: “The investigation against this group has been running for over a year.
“We have long acted with great determination against groups who send people into these war zones…. We would have conducted the raids either way.”
In the southern city of Munich, meanwhile, a court started the trial of 27-year-old German-Afghan dual citizen Harun P., accused of having joined the Sunni militia Junud al-Sham in combat in Syria.
The Munich-born defendant, who faces charges including membership in a foreign terrorist organisation, allegedly travelled to Syria in September 2013, received military training and joined fighting, including an attack on Aleppo prison.
He also faces a charge of attempted incitement to murder because he allegedly suggested to a militia commander that a 16-year-old German girl in Syria be killed for not wearing a veil, a proposal that was rejected.
Prosecutors allege P. tried to have the teenage girl killed because he feared she could later inform German security agencies about his activities.
The defendant left Syria for unknown reasons in March last year and was arrested on April 1 in Prague. – AFP