The Republic's Drugs Task Force, involving gardai, customs and the Naval Service, assisted in the seizure of an estimated £1.2 billion worth of Colombian cocaine off the Spanish coast last week, it is understood.
The operation by Spanish police and customs to seize the drugs involved a number of European forces co-ordinated through the Europol Drugs Unit.
It is understood the Irish service has been aware of the shipment and the operations to seize it for several weeks.
According to Garda sources, it is unlikely the drugs were destined for shipment into the European market through Ireland. It is more likely the drugs, on a cargo ship the Tamsaare, were destined for trans-shipment to smaller vessels from the Catalan coast of north Spain.
It is believed most of the cocaine supplied to the European drugs market arrives through the Catalan coast.
An attempt to land a large consignment of cocaine through the Republic was intercepted at Cork harbour in 1996. The 600 kg of the drug seized on the yacht in Cork is still by far the largest drugs haul intercepted by the authorities here.
It is understood the Spanish drug traffickers have connections with a number of Irish criminals, including one Dublin man who was involved in the drugs business in Spain up until recently. It is not clear if he was involved in the plot to smuggle the huge shipment into Spain last week.
The cocaine seizure in Spain has struck a major blow against the Spanish-Colombian network which has been supplying much of the European market for the drug for the past two decades.
The total haul taken from the Tamsaare, in an operation off the Canary Islands, is put at five tonnes. A further five tonnes of the drug were seized in Spain, along with a large quantity of heroin.
In the operation, headed by the Spanish investigating magistrate, Mr Baltasar Garzon, 40 people were arrested in Spain and 16 on board the ship. Mr Garzon is the senior Spanish official responsible for bringing the extradition warrant against the former Chilean president, Gen. Pinochet.
The drugs network involved in attempting to smuggle the cocaine to Spain involves criminal gangs from western Europe, Russia and south America.
The fact that the smuggling operation was effectively smashed illustrates the increasing success of the co-ordinated response by European and American anti-drugs agencies.
Police, customs and naval services in Europe are now working in highly efficient co-ordination. Most countries now have drugs task forces like that set up in the Republic two years ago to co-ordinate police and customs work, and make sure the Naval Service is available for interception operations.
On a European basis these anti-drugs forces are co-ordinated through the Europol Drugs Unit in The Hague, which acts as an intelligence-gathering and disseminating service.