A sergeant was searched and a phone seized during the operation.
A garda station in Munster has been searched in relation to allegations of the leaking of Barry Cowen's drink driving case.
The Laois/Offaly TD was forced to step aside from his post of Agriculture Minister last July when details emerged of the 2016 incident.
Deputy Cowen questioned how the information ended up in the public domain as well as the details of the case on the record, leading to a GSOC investigation.
The Irish Daily Star reports that investigators seized a phone during the operation last week.