A man is still being questioned by gardaí in Limerick over the activities of dissident republicans and other criminal activity in the city.
The man was arrested in the Ballinacurra Weston area of the city yesterday.
The arrest of the man, thought to be in his thirties, was described as "significant" by gardaí.
Gardaí have extended his period of a detention for a further 24 hours at Henry Street garda station.
He was detained under Section 30 of the Offences Against the State Act. Under this legislation, gardaí may keep suspects in custody for up to 72 hours before being either charged or released.
Yesterday's arrest comes only a few days after the detention last Sunday of three men by British police in Lancashire. One of those arrested at the weekend is thought to have connections with Limerick.
The arrests were part of a joint operation involving gardai and British police investigating criminal activity in Limerick and the activities of dissident republicans.