Up to a ton of cocaine, worth around 62.6m, has been found on a yacht off the south-west coast of Ireland.
Three British crew members from West Yorkshire are being held over the seizure, and a fourth man has been arrested on suspicion of conspiracy to import cocaine.
The drugs have an estimated street value of ?70mto ?80m (54.8m to 62.6m).
A spokesman for Defence Forces Ireland told Sky News it was one of Ireland’s biggest drug hauls of the last ten years.
Commandant Sean O’Fatharta said: “The vessel in question is currently being escorted by Irish Naval Service vessels, with the Irish Air Corps providing aerialcover.
“It is being taken to a port near Cork and is expected to arrive at some point this evening.”
It is understood the men on board the Makayabellaput up no resistance and will be arrested by the Garda when they arrive on shore.
The ship was identified by the National Crime Agency, which asked the Irish Navy for it to be intercepted.
A joint sea operation bythe Revenue Customs Service, the Naval Service and An Garda S?h? soon followed.
In a statement, the Joint Task Force (JTF) said the operation, which began in the early hours of Tuesday morning, took place in “challenging conditions” 200 to 300 miles south-west of Mizen Head, Ireland’s most southerly point.
It involved two naval vessels and a number of interagency personnel.
“The LENIAMH supported by LE ROISIN positively identified a suspect vessel in a covert surveillance operation,” it said.
“The decision was made by the JTF situated in the Naval Operations Command Centre in Haulbowline to deploy an armed Naval boarding party, which resulted in the successful detention by Revenue’s Customs Service of the yacht, suspected contraband and the crew of three.”
Ireland’s Defence Minister Simon Coveneyhas congratulated all the agencies involved for their “pivotal role in the success of the operation”.
It is believed the ship was destined for north Wales.