A crime gang alleged to have distributed fake euro notes worth 16 million euros ($22.6 million) throughout Europe since 2005 has been broken up by Bulgarian police, the European police agency said on Thursday.

In a joint operation with Europol and Spanish authorities, Bulgarian police searched 20 houses in the region of Plovdiv, the country's second biggest city, and seized equipment for making counterfeit notes.

Police arrested 17 Bulgarians, a spokeswoman for the Plovdiv police department said.

"This was an excellent international police operation, led by the Bulgarian authorities, that has delivered a massive blow to a major gang of counterfeiters," Rob Wainwright, director of Europol, said in a statement.

The counterfeit notes of 100, 200 and 500 euro denomination were mainly distributed in Belgium, France, Germany, Greece, the Netherlands and Spain but the forgeries affected the whole of the European Union, Europol said.

Bulgaria is trying to step up the fight against organised crime to avoid more sanctions from Brussels, which has already cut its access to millions in EU aid because of fraud.