A payroll system error saw a health service employee receive a payment of €1 million by mistake, it has emerged.
The error only emerged when the employee came forward to report the unexpected bank account transaction.
In a statement issued this afternoon the Health Service Executive said the incident, which occurred over a year ago, was "due to a combination of human error and procedural gaps".
The overpayment happened when the HSE introduced its PPARS staff records and payment system to a former health board and was caused by a data entry error.
"Due to pressure of work around the time of the first 'go live' a control report from the system highlighting the error was missed," the statement said. "This control step has since been strengthened and made a mandatory internal requirement before payments are issued."
Tánaiste and Minister Health Ms Harney revealed at the Joint Oireachtas Committee on Health and Children yesterday that the €120 million payroll system - installed in her department in 1999 - wasn't working properly and was being investigated by the Comptroller & Auditor General.
Replying to a query by Fine Gael TD Dan Neville, she added: "It's churning out cheques. I understand somebody got a cheque they shouldn't have.
"I have to say I'm concerned. If we got it wrong, we have to put up our hands and say we got it wrong," she said.
The Minister said she was informed of the problems late last week and is awaiting further briefings from her secretary general.
Fine Gael's spokesman on Health and Children, Dr Liam Twomey, said that the HSE's response was totally inadequate and was starkly different to comments made by the Tánaiste at the Health Committee yesterday.
"Today we see a HSE statement stating that the PPARS system is working well and will be extended. Who are we to believe?
"Either communication has broken down completely between the HSE and the Tánaiste or the HSE is involved in a cover-up."
"The HSE's statement has not dealt with issues surrounding costs of the project, fundamental errors which prevent the system being enhanced in the future or the fact that certain stakeholders have not bought into the system."
It is currently being used to pay 36,000 staff and is being rolled out to the remaining 70,000 HSE staff and 30,000 voluntary sector employees over the next few months.
PPARS is a unified payroll and personnel system that was introduced in 1999 in five former health boards and St James's Hospital.