In a large-scale raid against money laundering and organised crime gangs, German police on Wednesday searched 80 properties in 25 cities.
In the process, the police made 11 arrests and seized assets worth more than 2 million euros (2.3 million dollars).
More than 1,000 police officers were involved in the raids, which were directed against members of an international money laundering network.
The focus of the operations was the western German state of North Rhine Westphalia.
The office for the prosecution of organised crime at the Dusseldorf public prosecutor’s office is conducting the investigations, which are directed against members of a so-called hawala network, according to a police statement.
Hawala banking, which is illegal in Germany, is an informal money transfer system that allows customers to transfer large sums of cash abroad which, if sent through the banking system, would require the approval of the banking supervisory authority.
The suspects are alleged to have laundered funds from criminal activity in Germany to Turkey and Syria.
According to preliminary estimates, the transaction volume amounted to around 140 million euros.
Violence, armed robbery and hostage-taking are also believed to have been common practices when the gang needed to collect money.
The suspects also stand accused of wrongfully receiving social benefits, tax evasion and not paying their social security contributions.
A 39-year-old Syrian man suspected of terrorist activity was also arrested in the raids.
Police believe that he is or was a member of the Islamist Al-Nusra Front and plan to prosecute him separately.
The suspected money launderers are believed to have transferred a total of more than 100 million euros from illegal businesses in Germany to Turkey and Syria.
The investigation began after a chance find by the police, when officers discovered 300,000 euros in cash hidden in a gym bag during a routine stop on a motorway.