A Garda is being questioned tonight in Dublin in connection with the discovery of gun components.
The Garda who is on probation was arrested while he was out socialising yesterday.
He's suspected of possession of firearms and is being detained under section 30 of the Offences against the State Act.
The Garda, who's in his 20s, can be questioned for up to three days.
His home has also been searched.
The investigation is being led by the Assistant Commissioner in charge of Special Crime Operations John O' Driscoll.
Garda Headquarters confirmed this evening that the Garda had been arrested and that an investigation is underway but would not comment further.
He's the second probationer Garda to be arrested this week.
Another Garda also in his twenties was arrested and questioned yesterday in the south of the country in connection with a number of thefts from a Garda station.
He has since been released without charge and suspended and a file is to be sent to the Director of Public Prosecutions.