Three members of the Gardai - including a Superintendent and an Inspector - have been arrested on suspicion of corruption.
Several premises in the southern part of the country were also searched this morning as part of the operation, which is linked to an investigation into a Limerick criminal gang.
There have been two previous arrests of Gardaí as part of this investigation.
It's suspected information has been disclosed to the criminal gang about a CAB investigation into its activities.
Today's operation was led by the Assistant Commissioner for Special Crime Operations and resulted in three members of the Gardai being arrested.
One is a Superintendent and is being questioned over a suspected breach of a law dealing with the sharing of information.
An Inspector has been arrested for a suspected breach of the Misuse of Drugs Act and a rank and file member is being held for suspected conspiracy to pervert the course of justice.
All three are in custody and will be questioned on suspicion of breaking one or more criminal offences.