A West Yorkshire man has been arrested following the interception of a yacht with a suspected cargo of cocaine worth 80 million euro (£62.5 million).
Three other men, believed to be British, were being questioned by Irish drugs squad officers today after the 60ft Makayabella was stormed by the Irish Navy 200 nautical miles off Mizen Head - Ireland's most southerly point - in the early hours of Tuesday morning.
It was towed slowly to Haulbowline naval base in Cork harbour, arriving late last night.
The cargo of drugs, believed to be about one tonne, remains on the vessel at the dock while the three suspects are being questioned by the Garda.
The men were taken to the Bridewell station in Cork city where they can be held for a total of seven days.
The interception followed intelligence from the National Crime Agency (NCA) in the UK and the French custom service, through the Maritime Analysis and Operations Centre based in Lisbon.
Details of the naval operation were kept secret for more than a day-and-a-half.
The men on board put up no resistance to the armed Irish Navy team who had launched on smaller rib boats from the offshore patrol vessel the LE Niamh. Another major coastal patrol vessel, the LE Roisin, provided back-up during the operation.
The suspected one tonne haul of cocaine will have an estimated street value of 80 million euro, with some estimates suggesting it could be even higher, depending on purity.
If confirmed, it would be one of the biggest such drug seizures at sea in Europe this year.
The arrested men can be held for an initial period of 48 hours before a district court judge must sign off on an extended period of detention.
The passage around the south-west coast of Ireland has been well used in recent times by drugs smugglers bringing shipments from South America and Africa into Europe.
In 2007, a record 440 million euro (£344 million) of cocaine was seized in Dunlough Bay in west Cork when a UK gang botched an attempt to bring the massive haul ashore on a smaller boat and capsized in rough weather.
Most of the group, including two Englishmen, were arrested in follow-up operations and eventually given lengthy prison sentences.
Just a year later, a 400 million euro (£312 million)haul was intercepted on the Dances With Waves yacht about 150 miles off Mizen Head.
Three British men on board were later jailed for 10 years each for their part in the plot.
The National Crime Agency confirmed a 43-year-old man had been arrested in the Leeds area.
He was detained in the early hours of yesterday on suspicion of conspiring to import Class A drugs in an operation assisted by officers from West Yorkshire Police. He was subsequently bailed until January.
"The arrest was directly linked to the seizure made by the Irish authorities," an NCA spokesman said.
The Makayabella, a charter yacht, was tracked from the Caribbean and the international investigation also involved Venezuelan authorities.
All four people arrested in connection with the suspected smuggling plot are British passport holders and all are either originally from the West Yorkshire region or have connections to northern England.