Gardai are questioning a man following the Continuity IRA warning that 400 Irish people serving in the British armed forces are 'legitimate targets' for the terrorists.
The man, in his 40s, was arrested in a suburb of Limerick yesterday. He had attended last week's Sean South commemoration, where the threats were issued.
He is being questioned at Henry Street station and can be held without charge for up to three days under the Offences Against the State Act.
Last week, gardai raided a number of houses in the city as part of the investigation.
They initiated inquiries after a statement was read at Mount Saint Lawrence cemetery in Limerick, which contained a warning from republican prisoners in Portlaoise jail that Irish people became legitimate targets for the CIRA if they enlisted in the British armed forces.
A British Ministry of Defence spokesman said they were committed to protecting all Irish members in the British armed forces.
"There are 400 Irish men and women serving with the British armed forces in the army, navy and RAF and all are being informed of the Continuity IRA threats through internal communications.''
Gardai in Limerick foiled a Continuity IRA plot to murder a British soldier on a visit home to the city over the Christmas holidays.