Four members of the Hells Angels have been arrested in north-west Spain for allegedly smuggling 500 kilograms (1,100 pounds) of cocaine into the county with the aim of distributing it.
The Interior Ministry said the men, all Canadians, were arrested near the coastal city of Pontevedra, where one had arrived by yacht, allegedly having sailed from Colombia with the drugs.
One of the three men who met the yacht was "a known member" of the San Diego chapter of the Hells Angels and another had been under investigation for suspected drug smuggling by the Royal Canadian Mounted Police, a statement said.
The smuggling operation had been under police surveillance since July 30 and culminated when officers raided two vans loaded with cocaine and arrested the Canadians.
In a separate operation, police arrested two other persons whose nationality was not disclosed but who were "responsible for the delivery of the drug" to Spain.
The arrests were the result of collaboration between Spanish police and the US Drug Enforcement Agency, Canada's mounted police, Europol and France's tax authority.