Three men were arrested after gardaí seized drugs worth €768,000 during an operation in Co Louth on Monday.
A search in Castlebellingham lead to the discovery of 28kg of cannabis herb worth €580,000, and suspected cannabis plants with a value of €80,000,
A second search was carried out in Dundalk, where suspected cannabis herb worth €100,000 and cannabis plants worth €8,000 were seized.
The operation involved members of the Louth Divisional Drugs Unit along with the Drogheda Detective Unit and personnel from Dundalk Garda Station.
The three men, who are in their 30s, 40s and 50s, are being detained under the Drug Trafficking Act, 1996, at a Garda station in the north west. Investigations are ongoing.