Over €2 million worth of cannabis plants have been seized around the country.
The seizures were made during planned raids under Operation Nitrogen in Counties Kerry, Cavan and Roscommon.
Four men have been arrested, however one is being treated in hospital for injuries sustained while trying to evade capture.
The raids were carried simultaneously, led by members of the Garda National Drugs Unit, targeting the cultivation of cannabis.
1,800 plants, worth €1.3 million, were found in a unit at the Clash Industrial Estate in Tralee in Co Kerry, where two Vietnamese men were arrested.
One is being treated at Tralee General Hospital, after jumping from the roof of the building in an attempt to escape.
700 plants, worth around €560,000, were seized at a house in Carrigaloon, Virginia in Co Cavan, where a Chinese man in his 50s was detained.
And a Chinese man in his late 20s was arrested at a house in Falty, Oldtown, Athlone in Co Roscommon, where €240,000 worth of cannabis plants were found.
The men are being held at Tralee, Bailieboro and Roscommon Garda Stations under Section 2 of the Criminal Justice Drug Trafficking Act.
