MADRID, Spain (AFP)— Spanish customs agents said Monday they had seized eight tonnes of cocaine inside a container from the tiny Latin American country of Suriname in one of the largest such shipments to date.

The container arrived at the southern port of Algeciras and inside it was a metal structure made with a special alloy that was designed to confuse the customs agents’ scanning equipment, the Agencia Tributaria tax and customs authority said in a statement.

Even so, the scanner managed to detect that the structure contained “a large quantity of merchandise” which turned out to be eight tonnes of “very high purity cocaine”.

Police arrested three suspects, including the person who received the shipment.

Spain is one of the main entry points for drugs into Europe given its close ties with Latin America, which is the main source of cocaine, and its proximity to Morocco, a key source of cannabis resin.

On Friday night, two police were killed when their patrol boat was rammed by a speedboat driven by drug traffickers off the southern port of Barbate, 70 kilometres (40 miles) west of Algeciras.

Eight people were arrested over the incident, which also left another two police injured.

Interior Minister Fernando Grande-Marlaska said Monday the government would “continue investing whatever necessary” to work against drug smuggling in the Gibraltar Strait, where trafficking is rife.

But he ruled out resigning as demanded by Spain’s right-wing opposition and local police unions who have repeatedly asked for more resources to fight trafficking.