The £18 million (€26.6 million) cannabis haul discovered on Tuesday in Co Down would have been distributed throughout the Republic and Britain, the PSNI said yesterday.
Chief Supt Hayden Bell said the find followed an intelligence-led inquiry involving the Drugs Squad and Customs officers. The haul weighs 3.5 tonnes and is by far the largest drugs discovery in Northern Ireland.
Officers believe it was brought in in a single shipment before being discovered in a warehouse in Newtownards.
Chief Supt Bell said two men, both British subjects, were still helping police with inquiries. He refused to be drawn on questions of a paramilitary link.
"We know there has been a considerable drought of cannabis," he said. "Had an amount like this hit the streets there would have been considerable demand for it, and it would have reached Northern Ireland, southern Ireland and possibly back into the UK mainland."
Tuesday's find is significantly larger than the £3 million cocaine haul uncovered last June at Belfast International Airport and the £2.7 million consignment of cannabis found at Annahilt, Co Down, in 2004. The North's security minister, Paul Goggins, said the latest seizure "clearly demonstrates the effectiveness of our multi-agency approach".
"Cannabis is a dangerous drug and has the capacity to cause real harm. Working together, these agencies have been able to remove illegal drugs from our communities and take the profit out of organised crime."
Mr Goggins chaired the multi-agency cross-Border group tackling organised crime earlier this week in Co Derry.
Security sources are particularly satisfied that such a sizeable drugs recovery operation has been concluded successfully so close to the high-profile meeting of the cross-Border group which included both Garda Commissioner Noel Conroy and PSNI Chief Constable Sir Hugh Orde.
Ann Marie Gordon, head of investigations for HM Revenue and Customs in Northern Ireland, said her organisation was committed to working with partner agencies to halt the menace of drugs and the harm it causes to communities.