Three men were arrested tonight after cocaine worth half a billion euro (£403m) was seized in a yacht off the Irish coast.

Armed authorities stormed the 60ft luxury cruiser in international waters after European anti-drugs chiefs tracked it from the Caribbean.

The gang of two Britons and another man believed to be from Dublin had been at sea for more than a month when the Irish Navy, gardai and customs intercepted them.

The 1.5 tonne haul is one of the largest drugs seizures in Europe this year and is expected to eclipse last year's record find off Co Cork.

Irish Justice Minister Dermot Ahern praised the co-operation of several European countries for thwarting the smuggling ring.

"Today we have another practical and successful example of different agencies working closely together, sharing intelligence and achieving a fantastic result," he said.

Irish authorities swooped at 11am today in an operation code-named Sea Bight after a tip-off from the Lisbon-based Maritime Analysis and Operations Centre - Narcotics.

The vessel was traced for more than a month before navy ships moved in around 150 miles off the south-west coast of Cork.

Officers boarded the vessel and found dozens of packages of suspected cocaine hidden inside - destined for drug dealing gangs in Britain or Ireland.

The three men - aged between 44 and 52 - were taken ashore at the small fishing port of Castletownbere and were being held at local garda stations in west Cork.

The man believed to be originally from Dublin is understood to have had more than one passport.

The boat captured near international fishing grounds in the Atlantic known as Porcupine Bank was being taken ashore under armed guard.

Depending on forensic tests, the seizure is expected to be worth about 500 million euro (£403m).

Last year 1.5 tonnes of cocaine valued at 440 million euro (£323 million) washed up on the Cork coast near Mizen Head after an elaborate trafficking scam fell apart.

The smuggling ring was foiled when a boat used by the gang broke down in a heavy swell, and overturned dumping sixty-two bales of high grade drugs into the sea.

Yesterday the fourth man involved in the botched plan was jailed for 10 years. Three others were jailed in the summer for a total of 85 years after a 42-day trial. A fifth man, who had been on the boat, fled and was never caught.

The Lisbon anti-trafficking agency is backed by Ireland, Britain, Portugal, Spain, Holland, France and Italy.

The centre targets private ships, cruisers, yachts and planes primarily from South and Latin America and west Africa.

The operation has also identified smuggling routes which use west Africa as a staging post before shipping to Europe.

Coastline popular with traffickers

Famed for its beauty, the south-west coast of Ireland has long attracted visitors of all nationalities to its rugged shores.

But the coastline has also been regarded as a notorious drug trafficking route over the last two decades.

Last year's find of 440 million euro of cocaine, washed up at Dunlough Bay in July, was then the largest ever drugs seizure in Ireland.

Liverpudlian Gerard Hagan, who swam ashore for help as an inflatable boat carrying 1.5 tonnes of the drug overturned in rough seas, was jailed for ten years for his role in the international drugs smuggling operation earlier this week.

The 24-year-old, of Hollow Croft, was among four Englishmen arrested over the massive operation.

Three others - who were jailed for a total of 85 years after a 42 day trial - have lodged appeals against their convictions and sentences.

Another prominent Cork find was in 1996, when a yacht named the Sea Mist was discovered carrying 599kg of cocaine with a street value of 42 million euro.

The boat belonged to Cork-born Brian Brendan Wright, who was found guilty at a London court last year of heading-up a major cocaine smuggling operation.

Nicknamed 'the Milkman' because he always delivered, Wright, whose main address was in Chelsea, west London, denied the allegations.

Other major seizures include the July 1991 discovery of 28 bales of cannabis worth around nine million euro on a yacht, The Karma of the East, off Courtmacsherry, Co Cork.

Two years later in July 1993, gardai and naval service personnel launched a combined operation to lure the yacht, The Brime, to Loop Head in Co Clare where, after boarding, they found 25 million euro worth of cannabis.

In September 1998, customs officers and gardai found more than 300 kilos of cocaine on the catamaran, The Gemeos, at Kinsale Harbour.

In November 1999, naval personnel boarded the converted trawler the Posidonia and found 18 million euro worth of cannabis resin.