Madrid  - The European Union's biggest ring for forging euro notes has been dismantled in Bulgaria, Spanish police said Thursday.

Seventeen people were arrested in Bulgaria, where police seized 500,000 euros (700,000 dollars) in fake notes, after a joint investigation between Bulgarian, Spanish and other European police forces.

Three clandestine facilities printed notes of 100, 200 and 500 euros in the Bulgarian city of Plovdiv. The high-quality notes circulated in several European countries.

Police had been trying to track the ring down since the first fake bills were discovered in Spain in 2007.

Police searched 24 addresses, seizing forging equipment and computer materials.(dpa)