A machine pistol was seized on Saturday evening when gardaí stopped a vehicle on a major road in south Dublin.
The gun was discovered when the vehicle was halted on the N11 Dublin to Wexford road at Shankill by officers from the Garda National Drugs and Organised Crime Bureau and Emergency Response Unit.
A man in his 40s was arrested following the discovery and is being detained under the provisions of section 30 of the Offences Against the State Act 1939/98 at a south Dublin garda station.
Det Chief Supt Angela Willis, head of the Garda National Drugs and Organised Crime Bureau said: “The seizure of firearms and the arrest of those who are prepared to use them continues to be a priority for the Garda National Drugs and Organised Crime Bureau who remain totally committed to detecting and disrupting those involved and bringing them before the courts.”