The Justice Minister says it is up to the independent judge who monitors the use of phone tapping to decide if claims that have emerged should be investigated.
It has been suggested that tapping by the force took place in the early 2000's for 'political purposes'.
One detective garda was moved from his job in a unit after raising concerns.
Frances Fitzgerald says she has never used powers available to a justice minister to seek a phone tap on a politician, but suggested it could have happened in the past.
"In respect of allegations made in reports, they have not been very detailed but would appear - as I've said - they relate to matters alleged to have risen in the early 2000's.
"Of course many in this house will recall that at that time there were people who described themselves as political activists, who were at the same time engaged in activities in support of unlawful organisations," she said.