Detectives leading a probe into Garda corruption conducted targeted searches at a Munster Garda station.
The station was searched as part of an expanding operation into feared links between a criminal gang and several gardaí, including a senior officer.
Yesterday's searches are part of a long-running investigation into corruption that last May resulted in the arrest of three serving officers.
The unprecedented investigation led to the arrests and suspensions of a Garda superintendent, inspector and an experienced detective.
All are based in the south.
It is understood the searches yesterday were focused on any contacts between the officers at the centre of the investigation and other gardaí.
One line of inquiry is whether pressure was exerted on other gardaí not to log specific matters including penalty-points offences under the Road Traffic Act.
Once penalty-point incidents are logged on the Garda computer system, they are now virtually impossible to void without specific reasons being given.
However, the investigation is focused on whether some senior gardaí may have asked fellow officers not to log specific RTA incidents involving named individuals - thereby bypassing the new control mechanism. The individuals who allegedly benefited were associated with a feared crime gang.
Last July, a leading sports figure was the latest suspect to be arrested in a long-running probe into Garda corruption.
A source told the Irish Independent that the man arrested is believed to be "the link man" at the centre of the entire investigation. A garda, one of three members of the force arrested for questioning last May, was also suspected of conspiracy to pervert the course of justice.
The garda is currently suspended from duty by Commissioner Drew Harris.
He has been arrested twice as part of the investigation being carried out by detectives from the NBCI into alleged wrongdoing or corruption involving gardaí in the southern region.
The corruption probe, which has been ongoing for the past year, has included covert surveillance and examination of phone records.
It also focused on the suspected leaking of information by gardaí to members of a major organised crime gang.
This included information about a planned search and seize operation by the CAB, targeting members of the gang and other criminal associates with loose connections to the crime network based in the south.