Spanish and Portuguese police say they have dismantled an organization that used powerboats to import large quantities of drugs into Spain from Morocco and have arrested 15 suspects.

A statement says surveillance began when evidence emerged of a large-scale, well-organized smuggling operation based in southwestern Spain.

The gang allegedly used a network of specially-equipped piers and warehouses to receive drugs and was able to move part of its operation to southern Portugal when it discovered its activities were being watched, Saturday's statement says.

Investigators seized 2,400 kilograms (2.7 tons) of hashish in three separate cross-border raids, as well as 23 speedboats, four jet-skis, 12 vehicles, 4,750 liters (1,255 gallons) of unsafely-stored fuel and 463,465 euros ($510,100) in cash, the statement says.

It wasn't immediately clear when the arrests were made.