Serious weaknesses in payroll controls within An Garda Síochána have allowed overpayments of €3.1m to staff, according to an internal Garda audit.
A report by the Garda Internal Audit Service (GIAS) found a total of 1,804 gardaí, civilian staff and pensioners had been overpaid by €3.1m - an average sum of roughly €1,700.
Gardaí had received an average overpayment of €2,760, while the figure for civilian staff was €759. The highest average amount was for Garda pensioners at €2,849.
The audit, which was released under Freedom of Information legislation, found no attempts were being made to recover €863,170 in overpayments to 240 individuals before 2014 as An Garda Síochána was only focusing on cases after that date.
The majority of historic cases related to Garda pensioners who were overpaid an average of almost €3,600.
"There is concern that perhaps nobody is actively monitoring and managing these historic cases," the audit observed.
It noted that the historic overpayments, which date back as far as 1999, may not be recouped as no records were found that beneficiaries had been notified within the required six-month period that they had been overpaid.
The report said legacy cases would need to be written off where no notification had been issued, while it recommended that 10pc of pensions or pay should be deducted each year from individuals who had been made aware of overpayments.
The audit identified 11 individual "serious control weaknesses" as well as three "moderate" problem areas.
It found there was a key risk that the system for managing overpayments to gardaí was open to fraud because of the possibility that overpayments were "deliberate events to enrich one or more persons at the expense of taxpayers."
The audit concluded that it could only provide "limited assurance" that controls over the management of payroll overpayments were effective.
The main cause of overpayments was identified as the late notification of events, which affected pay. It accounted for about 83pc of overpayments.
The common root cause in a lot of cases were overpayments resulting from sickness and absence where gardaí and civilian staff took unauthorised leave but were still paid due to delays in payroll administrators being notified they had exceeded the permitted number of sick leave days.
Overpayments were also caused by incorrect salary points and increment dates being applied.
It found there was no explanation how an overpayment occurred in 12pc of sample cases reviewed.
The audit was carried out jointly by the GIAS and the National Shared Services Office, which oversees human resources and payroll administration for government departments and public service bodies.
An Garda Síochána said the recoupment of overpayments to 155 Garda pensioners was a matter for the Department of Justice.
It said seven out of 23 overpayments to gardaí had been fully recouped while repayment plans were in place for the remainder.
An Garda Síochána said most of 53 other cases related to individuals who were no longer serving gardaí and it was seeking to establish who had responsibility for them.