A man in his 30s was still being questioned by gardaí in Limerick last night in connection with feud-related activities in the city and suspected membership of the "Real IRA".
The man is well known to gardaí, and has served time in prison for burglary and larceny.
Yesterday gardaí extended his period of a detention for a further 24 hours at Henry Street Garda station in the city.
It's understood the man, who was arrested at 1.30 p.m. on Tuesday in the Ballinacurra Weston area of the city, is also being questioned about the alleged importation of arms to Limerick.
He is being detained under Section 30 of the Offences Against the State Act, which means he can be held for up to 72 hours.
Gardaí described his arrest as "significant" in the investigation into the activities of dissidents in the Limerick area.
This latest arrest follows the arrest of three men in England on Sunday who are still being questioned by anti-terrorists police in London following the discovery of weapons linked to dissident republicans.
While the three men are English, it's understood that one of them has strong connections with Limerick.
The three were arrested in Lancashire on Sunday after a search of a commercial premises in Morecambe. Two handguns and a rifle linked to dissident republicans and criminal activity in Limerick were recovered.
The three men were transferred from Lancashire to a central London police station, where they can be held for up to seven days under the Terrorism Act 2000.
According to gardaí, the arrests were part of a joint operation involving the Garda and English police investigating criminal activity in Limerick and the activities of dissident republicans and the Continuity IRA.
English police said that the guns seized were not for use in England, and it's understood that some of those arrested may have links with a breakaway republican group.
A spokeswoman for the London Metropolitan Police Service confirmed last night that all three men were still in custody in London.