Spanish authorities say they have seized 1.5 metric tons (1.7 tons) of cocaine and arrested 10 suspects from a ring that imported the drug from South America via large ships that offloaded the cargo off Spain's northern coast to smaller recreational boats for shipment ashore.

The Civil Guard said in a statement Friday that agents arrested four Spaniards, three Argentines, a Briton, a Dutch citizen and a Paraguayan in raids in four different regions of Spain.

The cocaine was found in a house in the northern province of Vizcaya. Also seized were 12 vehicles and boat navigation equipment.

Authorities started their investigation after Civil Guard agents in June stopped two vehicles in northeastern Zaragoza province carrying nearly 100 kilograms (220 pounds) of cocaine and detained the two drivers.