Officers arrested the suspects last week in the southern provinces of Cadiz and Malaga as well as in Spain's North African enclave of Ceuta, the National Police said in a statement.

Among those arrested was the alleged leader of the ring, a former British Royal Navy marine "with extensive nautical knowledge" who is suspected of transporting the drugs by sea.

The unidentified man, who lived in a "luxury urbanisation" in Cadiz, had "ties with criminal organisations in European nations such as Britain and Ukraine," where the ring sent its drugs.

He owned several firms which sold and rented boats that he used to transport the hashish as well as shell companies to launder the money earned from drug smuggling, police said.

Police seized a sailboat and two yachts as well as 1.6 tonnes of hashish as part of the operation, which was carried out in cooperation with Britain's National Crime Agency.

Spain's close ties with its former colonies in Latin America, a major cocaine-producing region, and its proximity to Morocco, a major hashish producer, have made it a key entry point for drugs bound for Europe.