Portuguese police have confiscated a total of €380,200 in fake €200 notes, calling it "the world's largest seizure of counterfeit euro".
The 1,901 fake banknotes were discovered in a police operation in the northern city of Porto on Tuesday.
A 46-year-old man was also arrested, but police have not yet revealed his identity or nationality.
The authorities said the counterfeit bills were "of exceptional quality".
Officials added that the operation had been active since 2002 in numerous countries, including Spain, Germany, Italy, Bulgaria and Portugal.