Gardaí have arrested a woman bringing to four the number being held in connection with an attempt to buy firearms and high-powered weaponry in Cork.
The woman is in her 20s and is being detained at Mayfield Garda Station.
Gardaí are continuing to question three men who were arrested last night.
It is understood the firearms involved handguns, rocket-propelled grenades and an AK47 assault rifle.
The three men were arrested on the outskirts of Cork city last night following a covert garda operation that has been ongoing for several months.
It was led by detectives from the southern region in Cork and Limerick, and backed up by the National Surveillance and Emergency Response Units.
A criminal gang involved in the drugs trade in Limerick, the intended destination of the guns and weapons, was the main focus of the operation.
Gardaí broke cover late last night near Glanmire, on the eastern outskirts of Cork city.
It is understood two of the men were arrested while the weapons were being exchanged in the carpark of a hotel in the area.
A third man was arrested nearby a short time later.
Gardaí said that no weapons were acquired by criminals in the course of their operation.
The three men who were arrested are being questioned at Togher and the Bridewell garda stations.
Two are brothers from Cork city, the third is from Tullamore in Co Offaly. All three are aged in the 20s and 30s.
