The discovery of 75kg of cocaine along the Clare coastline is thought to be the first known seizure of a so-called ‘narco-torpedo’ in Ireland.

The torpedos are one of a number of sophisticated ‘narco-submarine’ methods used by South American drug cartels to transport major consignments across the Atlantic to Europe.

The discovery is another indication of the scale of the cocaine trade passing through Irish waters — in some cases destined for Ireland, in other cases bound for Britain or Europe.

A member of the public reported the discovery of the cylindrical device to Revenue on a beach in Clare on Monday, though the device is thought to have been there since the end of August.

The 2m-long metal tube was stuffed with 75 1kg bags of cocaine, some with markers. Customs gave an initial street valuation of €5.25m, but, given its likely high purity, it could be multiples of that.

“To my knowledge, this is the first time such a device has been discovered in this jurisdiction,” said Liam Peakin, head of Customs Drug Law Enforcement.

He said the torpedos are “one of the most effective methods” as they are typically concealed under the water line. He said international intelligence shows that anywhere between two and six such torpedos are attached to a cargo ship or other maritime vessel.

“They are installed at some point in ports, covertly by narcotics smugglers using scuba divers. They are then removed at the point of destination,” said Mr Peakin, noting that people in the vessels are typically unaware of them.

The torpedo recovered was thought to have been attached to a vessel by clamps that may have broken off.

Mr Peakin said it is “pure speculation” where the drugs had come from or where they were going.

However, he said it is a clear indication of the “massive” trade in cocaine consignments that are travelling through Irish waters.

“It’s an indication of the market for cocaine,” said Mr Peakin. “It’s also an indication of the ingenuity of these traffickers. It never ceases to amaze me.”

The haul is the second major cocaine seizure by Revenue in the last week following the discovery of 33kg of the drug in the Midlands.

In March 2015, 25kg of cocaine was located at Cork Port directly imported from South America.

In December 2014, 300kg of cocaine from Columbia was seized in Portsmouth, England, following a joint Irish-British surveillance operation.

And 1.1 tonnes of cocaine was seized aboard the yacht, Makayabella off the Cork coast in September 2014.

In July 2007 and November 2008, there were two seizures, each of 1.5 tonnes of cocaine, off the Irish coast.