A man in his fifties is being questioned by gardaí following the discovery of an explosive device in the car park of a Dublin hotel on Saturday.
The viable device was found in a Northern Ireland-registered car at the car park of the Finnstown Country House Hotel at 9pm.
The device - comprised of fertiliser in a beer keg or milk churn - was described as viable but was not primed.
Gardaí were called to the scene and the hotel was evacuated. An Army bomb disposal team attended the scene and made the device safe. Guests were allowed to return to the hotel a number of hours later.
The man in custody understood to be a dissident republican (55) who was arrested in a follow-up search at a flat in west Dublin where bomb-making equipment was also found.
The man is being held at Lucan Garda station and can be detained for up to 72 hours.