Officers descended on 19 houses in Naples, Italy and Germany on Thursday and seized fake banknotes amounting to €160,000 as well as a gun and cocaine.
A gang printing and distributing counterfeit euro banknotes was broken up by Europol and German and Italian police on Thursday.
Officers descended on 18 properties in Naples, Italy, where the operation was based, and one house in Germany where the notes were distributed.
Four Italian nationals were arrested on Thursday and more than €30,000 in cash together with accounting records and computers were seized.
During the investigation police also seized a quantity of cocaine, a gun and counterfeit money for a value of about €160,000 - including a forgery of the new €100 note just six months after its official release by the European Central Bank.
The suspects are believed to have ties to the Camorra mafia clan. In a statement, Europol said that apart from printing fake money in Italy and selling it in Germany, the group was involved in drug trafficking and tax fraud.
"The main suspect is also believed to be involved in the trafficking of different illegal commodities including drugs, stolen vehicles and falsified documents," Europol said. "He is suspected of distributing these illegal commodities, acquired by his associates living in Naples and connected to the Camorra."
The operation was led by the German Regional Criminal Police of North Rhine-Westphalia and the Italian Finance Corps of Rome and Naples.
Law enforcement from the Belgian Federal Police and the French National Police also supported the investigation. Officers have also obtained a judicial security order of €415,000, issued by Germany.
This investigation is part of the Italian DIA Project ONNET, an EU-financed initiative to tackle mafia-type organised crime groups active in Europe.
It took place weeks after raids across Italy and Germany saw some 30 members of the 'Ndrangheta organised crime syndicate arrested in an operation involving more than 800 police officers.