As part of the operation, which resulted from an investigation launched last year, the vessel used for transporting the drugs was also seized from the detainees, five of whom have already been presented to the judicial authorities and have been remanded in custody, the police said in a statement.

The investigation, under the responsibility of the National Unit for Combating Drug Trafficking of the Judiciary Police, was aimed at dismantling this organisation, "suspected of bringing large quantities of hashish from North Africa into Portugal by sea and then being shipping it overland to several European countries," the communiqué explained.

The PJ said that in this operation, called "Catavento" and supported by the Navy and the Air Force, "it was possible to locate and then intercept a fishing vessel that the criminal organization in question was using to transport approximately 3,500 kg of hashish, which were seized together with the vessel" in the middle of the Atlantic Ocean, off Cabo de São Vicente.

The detainees, a Portuguese citizen and six foreigners, are between 29 and 52 years of age.

The investigation, which was also supported by the Cuerpo Nacional de Policía de España and the Maritime Analysis and Operations Centre - Narcotics (MAOC-N), based in Lisbon, will continue to gather more evidence, the police added.