Spanish police have arrested five members of a drugs gang, several Dutch nationals among them, during a raid in the Catalan city of Reus on Sunday, Spanish media reported.

The gang, whose members come from Albania, Lithuania and the Netherlands, had hit upon a “very sophisticated method” to hide the drugs by impregnating 16 tonnes of wood pellets used as fuel for wood burning stoves with liquid cocaine, local paper Diari de Tarragona said.

Police discovered that the pellets, which had entered the country legally from South America to Spain in sea containers, were stored for three months to “cool off” before being taken to a place where the drugs were extracted.

The premises had been watched for months when a lorry with a foreign number plate arrived to pick up a load of pellets and police sprung into action. In all, 920 bags of pellets, each weighing 18 kilos, were found.

The gang also had a space to package, seal and store the drugs, which were then transported across Europe. Police also impounded five kilos of MDMA, two hydraulic presses, a lorry and luxury car.