Cannabis with a street value of worth more than £10m (€14.8m) was seized from a warehouse in the North today.
Up to four tonnes of the drug, in bars and packed onto pallets, were discovered when police and HM Revenue and Customs officers raided industrial premises at Newtownards, Co Down.
It is thought the haul of cannabis, the biggest ever uncovered in the North, may have been destined for the Republic.
Two men arrested were being questioned tonight by detectives involved in the operation.
Officers were still trying to work out the final weight of the batch in a bid to establish its exact value.
Sources predicted it would comfortably surpass £10m (€14.8m).
Assistant Chief Constable Peter Sheridan, head of Crime Operations, praised those involved in striking a major blow against the drugs gangs.
He also stressed the seizure had come a day after police, customs and assets-stripping agencies met in Co Derry to assess the cross border crime threat.
Mr Sheridan said: “I would like to congratulate my officers and our colleagues in HMRC on this success.
“This is proof of our determination to tackle the scourge of illegal drugs.
“At a strategic level, law enforcement agencies on both sides of the border have just taken part in a conference on organised crime in Limavady. At an operational level, agencies have worked together to protect the public and take drugs out of circulation.
“Such a co-ordinated approach is paying dividends which I am sure is welcomed by everyone in our community.”
Security sources also revealed there was no immediate suggestion of paramilitary involvement.
The arrests and seizure came as part of the multi-agency Organised Crime Task Force’s developing offensive on illegal drugs in the North.
Local Strangford MP Iris Robinson congratulated those who had succeeded in keeping the huge haul off the streets.
She said: “Police and customs officers have skilfully and very professionally managed to prevent this massive consignment from being distributed across the North.
“It is not yet clear who was responsible for this criminal act or whether there was paramilitary involvement but I would encourage anyone with any information at all in relation to these drugs to immediately contact the Police Service of Northern Ireland.”
She added that the covert operation had obviously been ongoing for some time.
“I hope that it will be followed up by successful criminal charges and convictions for those responsible for smuggling, hiding and potentially distributing this material.”
The Northern Ireland Security Minister, Paul Goggins, claimed the seizure proved the authorities’ enforcement efforts were paying off.
Mr Goggins, who also chairs the Organised Crime Task Force, said: “Cannabis is a dangerous drug and has the capacity to cause real harm. I congratulate both PSNI and HMRC on taking such a large amount off our streets.
“This clearly demonstrates the effectiveness of our multi-agency approach.
“Working together these agencies have been able to remove illegal drugs from our communities and take the profit out of organised crime.”