The Department of Health has estimated that up to 2,000 staff are employed in the health service on a temporary basis to provide cover for personnel on maternity leave.
The Health Service Executive (HSE) has told its board in recent months that the Government's decision to extend maternity-leave provisions has had a significant effect on its ability to live within its official employment ceiling.
Last year, the Government agreed a new employment limit of just over 108,000 for the health service.
However, the HSE board was informed by management over the summer that the actual number of whole-time equivalent staff (WTES) on the payroll had risen to 110,634 by last April.
HSE management said "a continuing further significant factor on ceiling compliance is the growth in employment in the last number of months due to the introduction of enhanced maternity-leave entitlements".
The Government extended paid maternity leave arrangements from 22 to 26 weeks and unpaid arrangements from 12 to 16 weeks.
In a statement, the Department of Health said the HSE estimated that by the end of June "the impact of maternity leave on the overall level of employment is in the region of 2,000 whole-time equivalents".
"While the approved employment ceiling for the public health service has not been adjusted in respect of maternity leave, the HSE, with the agreement of the Departments of Health and Children and Finance, now qualify the total number of people employed by way of a footnote explaining the number of people employed as locums to cover maternity leave.
"An employee whose post is filled while on maternity leave remains on the payroll of the health agency, resulting in two WTES being counted against the particular post. The purpose of the footnote, therefore, is to explain the effect of maternity leave on overall employment levels," the Department of Health stated.
Minister for Health Mary Harney told the Dáil recently that in actual terms there were close to 130,000 people employed in the delivery of public health and personal social services. She said the vast majority of these provided direct services to patients and clients.
However, the Minister also signalled that HSE staff numbers could be cut in the future on a voluntary basis.
She said that about 16 per cent of the staff in the health system were in administrative roles, a figure which was at 18 per cent in the NHS.
"The HSE is currently carrying out an audit of management and administration, which I support. I am not saying we have the right balance.
"There is scope for a voluntary redundancy programme and I hope that can be discussed in the new health forum that will be established," she said.