Spanish police intercepted in Venezuela more than 7 tons of cocaine hidden in a consignment of machinery bound for Spain, authorities said Thursday.

Thirteen people were arrested, five of them in Spain and eight in Venezuela, during the operation, which allowed authorities to break up major drug trafficking organizations.

During the operation, which was coordinated with Venezuelan security forces, police conducted eight raids in Spain, one of them against a heavy machinery company through which the network laundered the money it obtained from drug trafficking.

The ringleaders were Spaniards and lived in Madrid.

The network intended to introduce the drugs through the northern Spanish port of Bilbao hidden beneath the floorboards of construction machinery.

The investigation into the illegal activities began in February, when police learned that one of the men arrested, identified only by the initials L.M.J., was preparing to ship heavy construction machinery from Spain to Venezuela.

The intention, investigators said, was to pack the machinery with cocaine and return it to Spain later on cargo ships.

The shipment of the machinery to a Venezuelan company had been carried out by a Madrid firm headed by L.M.J. and a relative.

Thanks to information from Venezuelan authorities about the type of machinery and the receiving companies, security forces were able to seize 6,700 kilos (14,757 pounds) of cocaine hidden in the machinery ready to be shipped back to Spain.

Searches of Madrid properties belonging to L.M.J. and his associates led to the seizure of 30 luxury vehicles, more than 100,000 euros ($143,690) in cash, fake pistols, jewelry and watches and a large number of documents.

The suspects also had bank accounts holding millions of euros.