Local authorities have spent €214,000 on private detectives to crack down on illegal waste, investigate protected disclosures and on planning enforcement over the past three years.
The biggest spend was in Dublin where the city council paid out €72,413 on investigations since the beginning of 2017.
According to details released under Freedom Of Information rules, €58,548 was paid out for an investigation into a protected disclosure in 2017.
A further €9,000 was paid to an investigator for another protected disclosure inquiry in 2018, while €2,713 was spent on a third whistleblower case.
The council also spent another €2,152 on "investigation of a complaint" last year, while €543 was spent on a planning enforcement probe.
In Limerick, the total spend was €35,781, with more than half of those bills - or a total of €19,035 - incurred in 2018.
The local authority said it engaged private investigators for the services of notice under planning legislation.
Kildare County Council has run up €27,801 in private detective bills since 2017, with almost all of that money spent on environmental enforcement cases.
A smaller bill of €440 was also paid in a case involving "recovery of rates".
The council declined to provide further detail on what the expenditure involved.
Cork City Council spent €31,300 on private detective services over the three years, according to a list of payments it released.
The council provided no further details on what the expenditure involved, but the company which received the bulk of the money specialise in insurance, private investigation, document and summons service and personnel screening.
In North Dublin, Fingal County Council said it had spent €14,300 on the services of private investigators over the past two years, with no expenditure recorded in 2017.
The council would not provide details on why and when such services were used, saying only that it was done on a "case by case basis with no specific criteria or scenarios".
Monaghan County Council ran up a bill of €8,555 on private investigator services last year, according to records released under FOI.
It said the expenditure related to an "environmental enforcement" case.
In Meath, a total of €13,463 was spent on private detective services over the past three years, with more than half the bill from last year.
The county council said that the reasons for hiring such services included the investigation of major illegal waste cases.