Three men were arrested over the weekend in Co Limerick as part of an ongoing investigation into dissident republican activity, gardaí have said.
The operation involved members of the Special Detective Unit, assisted by members of the Garda Emergency Response Unit.
They stopped and searched two cars, one of which is thought to have been taken without authorisation.
The operation occurred at Kyletaun, Rathkeale, Co Limerick, early on Saturday morning, shortly before 2am.
The car was searched by gardaí and what was thought to be a firearm and ammunition, subject to ballistic examination, were discovered and seized.
Arrested
Three men were arrested and are currently being detained at Henry Street Garda Station in Limerick. They are being held under section 30 of the Offences Against the State Act, 1939.
The three men are aged in their mid-20s to late 30s, gardaí said.