GardaĆ in Clare are questioning a man after they stopped a car and discovered an estimated six kilograms of herbal cannabis.
The vehicle was intercepted and stopped on the M18 motorway near Latoon last night.
The intelligence-led operation involved members of the Clare divisional drugs unit and local officers.
The man in his 40ās was taken to Ennis Garda station where he is still being questioned.
During a follow-up operation in Limerick City, a further six kilos of herbal cannabis were discovered.
The drugs and the vehicle were seized by gardaĆ and will be forensically examined.
The entire haul is believed to be worth almost ā¬250,000 subject to analysis.
The man is being held in Ennis stationĀ under the provisions of section 2 of the Criminal Justice (Drug Trafficking) Act 1996 as amended.