The Department of Public Expenditure and Reform has confirmed a trawl of allowances in the public sector two years ago failed to disclose the so-called top-up payments to senior health sector employees.

Earlier, the master of the National Maternity Hospital Dr Rhona Mahony said she had been vilified about a €45,000 addition to her salary of €236,000 - adding that this had been utterly unwarranted.

Dr Mahony said that the €45,000 sum was in respect of professional fees from private patients attending the National Maternity Hospital.

RTÉ asked a spokesperson for Dr Mahony whether the €45,000 payment was the sum total of her private earnings, and whether it was in respect of patients personally treated by her.

The spokesperson said she would not be commenting further.

She said she had the same contractual terms as all other medical consultants in the Irish health service and that the existence of this income had been reported to the HSE in May 2012 as part of a routine confidential internal audit carried out by the HSE.

Dr Mahony stressed that she had never received any additional remuneration from the health service or any other source, including fundraising and charitable donations.

Earlier, Taoiseach Enda Kenny said the Government will take action to see that unauthorised, unapproved, non-exchequer top-ups that are clearly in breach of public pay policy will end.

He said the HSE are now preparing the report to present to the Minister for Health.

He said people have contacted him who worked very hard in a voluntary capacity to raise funding for many of these hospitals.

He said they do not want this kind of situation to continue and it will not continue.

The Oireachtas Public Accounts Committee is to open an investigation into the payments to senior health managers next week.

Chairman of the Oireachtas Health Committee Jerry Buttimer has said the committee will be calling in officials from the HSE and voluntary hospitals at the earliest opportunity to discuss top-up payments and governance issues.

Separately, the PAC heard today that the Director of the National Gallery Sean Rainbird had been awarded an additional €40,000 on top of his salary of just under €100,000 to visit his family in London 40 times a year during the five-year duration of his contract.