European police forces have dismantled one of the drug clans from a Balkans cartel regarded as one of the biggest drug rings operating in Europe, Spanish police said Wednesday.

A total of 12 people have been detained. Five of them were held in the eastern Spanish port city of Valencia. The others were held in Croatia and Bosnia, including the suspected leader of the Balkans cartel.

The ring was discovered after Spanish police noticed the presence in Barcelona of a former Croatian marine who contacted drug traffickers in the Spanish city.

On May 11, five suspects were caught in Valencia when trying to bring ashore 368 kilogrammes of cocaine which had arrived on board a freighter.

The drug had been sent by traffickers based in Brazil to the Netherlands, where it would have been worth more than 11 million euros (15 million dollars) on the black market.

Spanish police also seized five pistols and an armoured vehicle.

The US Drug Enforcement Administration (DEA) participated in the investigation.