A "significant quantity of cocaine" has been found after a catamaran was seized in the English Channel in an operation involving Irish Defence Forces.
Five men have been arrested on suspicion of drug smuggling.
The UK’s National Crime Agency said that a Border Force boat intercepted the vessel off the southwest coast of Cornwall and escorted it to Newlyn Harbour.
An Irish Naval vessel and an Air Corps maritime patrol aircraft took part in the inter-agency operation.
They conducted a surveillance operation off the south coast of Ireland prior to the detention of the vessel.
A spokesman for the NCA said: "As part of a National Crime Agency-led operation, the Border Force cutter HMC Vigilant intercepted a catamaran off the south west coast of Cornwall and escorted the vessel into Newlyn harbour on Thursday morning.
"The investigation is ongoing and a significant quantity of cocaine has been removed from the boat.
"National Crime Agency and Border Force officers, supported by Devon and Cornwall Police, remain at the scene as searches continue.
"Five men have been arrested for drug trafficking offences and are now being questioned by National Crime Agency officers."
The quantity of drugs found on the vessel is expected to be confirmed once a thorough port inspection has been completed.
The operation comes six weeks after hundreds of parcels stuffed with drugs were seized from a yacht in the same port.
NCA and Border Force officers have intercepted a catamaran containing cocaine off the coast of Cornwall.— NationalCrimeAgency (@NCA_UK) August 30, 2018
The NCA led operation has resulted in a significant amount of cocaine being removed from the vessel in Newlyn harbour and five men arrested on drug trafficking offences. pic.twitter.com/f3ZzFolev9