A huge haul of ecstasy and cannabis, as well as a press for making ecstasy tablets were discovered in the search of a house in Castletown yesterday evening.
Nine men were arrested in an operation, which saw the house in Castletown and industrial units in Dublin searched.
The search in Castletown involved local gardai working with officers from the National Drugs Unit.
The operation in Dublin and Meath saw the seizure of six firearms, including handguns, a machine pistol and drugs with an estimated street value of at least €3million.
The Garda National Drugs Unit has been investigating the activities of the gang involved for the past few months.
Gardaí say five of the men arrested are key figures in the drug trafficking gang and the others arrested are believed to be customers.
The nine men, aged between 29 and 46, are being detained at Blanchardstown, Clondalkin, Finglas, Ballymun and Store Street Stations.