Gardaí have released seven men who were arrested in Co Cavan on Sunday after the group were found in possession of balaclavas and machine guns.
Gardaí believe the men, aged from in their 20s to 40 years, were on their way to target a local businessman as part of an extortion plot.
Six of the men were released on Monday night, while one of them had been released earlier on Monday.
Gardaí said a file on the case is to be sent to the Director of Public Prosecutions.
The suspects were arrested on Sunday night following an intelligence-led operation by gardaí in the Bawnboy area. It is understood the men had been under surveillance at the time.
Investigators believe the gang was on the way to threaten the businessman or someone close to him in the hope of extracting money from him.
The businessman had previously been investigated by the Criminal Assets Bureau (Cab), which investigates wealth which may have been accumulated through criminality.
As well as balaclavas, gardaí recovered two automatic weapons and one semi-automatic pistol.
Some of the suspects are believed to have extensive links to organised crime in Northern Ireland and the Republic. Two are from Northern Ireland and five are foreign nationals living in Dublin.
As part of the operation, gardaí in Cavan identified four cars they believed to be connected to the extortion plot.
Following searches of the four cars, the seven men were arrested and firearms and ammunition located.
