Gardaí and the Revenue Commissioners installed tracking devices on 29 vehicles last year.

It is the first time that figures have been released showing the extent of surveillance among state agencies.

Surveillance was mounted in another 40 cases where Gardaí or the Revenue Commissioners thought it could be used to help with a prosecution.

The figures were released in a review of surveillance for the 12 months up to last July, carried out by Justice Robert Eagar of the High Court.

Justice Eagar said he was satisfied that all surveillance operations were carried out in accordance with law, and were justified in the circumstances.