Spanish and British police have broken up a drug-smuggling ring based on Spain's Costa del Sol, arresting 34 people and seizing 3.8 tonnes of hashish, Spanish police said on Saturday, according to Reuters. The leaders of the ring included a British former policeman and a former British marine. It said the operation, launched last October, had been difficult because the leaders used their experience to lecture other members of the ring on police investigation techniques. In simultaneous raids in several cities in Spain and Britain, police seized 3.8 tonnes of hashish, arrested 34 people and confiscated luxury cars and more than 100,000 euros in cash. The statement did not say when the raids were carried out. The police statement listed 12 people arrested in Spain, including 10 Britons and two Spaniards. The Marbella-based members of the group are alleged to have obtained the drugs and prepared them for smuggling to Britain. Investigators believe the group used property companies to launder the proceeds of the drug sales. Spanish police said a further eight people were arrested and 2.36 tonnes of hashish seized in a separate operation on Spain's south coast. Those arrested included six Poles, a Romanian and a German. In a house where one of the group lived, Spanish police found a Kalashnikov assault rifle, two automatic pistols with silencers and a large quantity of ammunition.