One man was arrested and two others were formally charged, according to an official statement by Spain's Civil Guard.
They had attempted to sell forgeries of six paintings by Miró, two by Matisse and one by Picasso to collectors and galleries for hundreds of thousands of euros.
The operation began last June after police in Leida stopped a Spanish man crossing the border from the Principality of Andorra. They found paintings in his car allegedly signed by Miró together with documentation of their supposed authenticity.
Experts consulted by the Historical Heritage Group of the Civil Guard confirmed that the paintings were fakes.
Investigating officers placed the man under observation. They later spotted him travelling frequently between Andorra and Zaragoza where he met art dealers and collectors and tried to sell them the forged paintings.
When the police had gathered enough evidence they arrested the man and charged two presumed accomplices, including a gallery owner in Zaragoza who allegedly acted as an intermediary.
The Civil Guard claims that the investigation thwarted the sale of two forged Miró lithographs that originally represented a medallion made to mark the centenary of Picasso's birth in 1981.