The technology enables the smuggler to locate a consignment on the sea bed. 'The satellite navigation can provide a computer print-out of the exact position, using fixed co- ordinates, accurate to within 20 feet of where it was first dumped,' Liam Herlihy, director of the Irish Customs national drugs team, said.
The latest cannabis batch was found accidentally by a French trawler off Kinsale, Co Cork, on the south coast of the Irish Republic. It was sealed in waterproof packaging.
Its discovery has convinced Irish customs officers that smugglers have been operating an offshore transit point from which consignments can be collected as required. Sea dumping reduces the risk of detection of a whole consignment brought on to land.
British Customs officers are due to join Irish colleagues in Cork today to try to determine whether the consignment of Moroccan cannabis found off Kinsale is from the same source, and placed there by the same syndicate, as the pounds 9m batch found in a similar underwater dump off Milford Haven in Wales in May.
The first such large-volume offshore dump was discovered off Portugal late last year.
Investigators are unclear on whether the Kinsale cannabis was destined for sale in the Irish Republic, or for transit by road and ferry to Britain. One of the largest previous seizures - worth Ir pounds 7m ( pounds 6.7m) - at Courtmacsherry, Cork, in July 1991, was made from a British- registered yacht.
In the last 10 days the French trawler Maria Catherine, based in Brest, has lifted 39 bales averaging 22kg each from off Kinsale. The street value of the latest consignment is estimated at Ir pounds 9.24m ( pounds 8.88m).
Under direction from Irish Customs, the French vessel, itself using satellite navigation, to trace the point where the first bales were found, is continuing to trawl for more.
Mr Herlihy told the Independent that he was liaising with British counterparts over the significance of the numbering system used in markings on the foil-wrapped bales, which were all in sealed vacuum- packed plastic.
Close similarities would point to the same syndicate being involved, and suggest that the Irish dump could have been set up to reduce the risk of detection after the Welsh find. Mr Herlihy said that the two teams would also try to determine how long the dumps had been operating.
The Kinsale find comes after a series of discoveries in Cork and Kerry in the last two and half years that some claim points to the area being used as a 'back door' into the United Kingdom.
The combination of sparse population and rugged coastline along the south-west of Ireland makes it particularly difficult to monitor. The largest Irish seizure occurred in July this year when two tons of cannabis, with an estimated street value of Ir pounds 20m ( pounds 19.2m), was found on 65ft ketch, eight miles off Loop Head, Co Clare.Reuse content