Gardai are questioning three men and a woman in connection with a criminal conspiracy to import a large quantity of guns in Cork.
The three men were arrested on Friday night after what Gardai described as an `intelligence-led operation when the arms were seized. It is understood the arms were not destined for paramilitary use.
A Gardai spokeswoman said: "The arrests were made as a result of an intelligence-led operation and involved the attempted purchase of a sizeable quantity of firearms and other high powered weaponry."
The arrests were the culmination of a long operation involving dozens of detectives and uniformed police, backed up by members of Ireland`s elite Emergency Response Unit and the National Surveillance Unit.
The arrested men, two in their 20s and one in his 30s, have been detained under section 30 of the Offences Against the State Act and can be held for up to 72 hours before being charged or released.
Late yesterday police also arrested a woman in her 20s for questioning about the arms. Police said the operation focused primarily on Cork and Limerick but that the organised crime networks targeted stretched further across the country.
Garda Superintendent Kevin Donohoe said: "This particular phase of the operation involved assistance from law enforcement agencies overseas and a covert element.
"No weapons were actually procured by criminals in the course of their efforts.
"This was an extensive operation and the results achieved to date are significant in the Garda Siochana`s efforts to tackle organised and serious crime networks throughout the country."