A HSE ambulance had to be written off following a crash in Dingle last year.
It was one of five ambulances nationally that had to be taken off the road permanently following collisions in 2023.
This information was contained in a HSE internal audit.
The report said there were currently no reserve emergency ambulances available to provide the service when such a vehicle is unexpectedly written off or not available for service.
The audit also showed that 45 ambulances nationally were still being used after six years, including 16 in the south, when such vehicles should have been put off the road up to two years previously.
In response, the National Ambulance Service said it received extra capital funding in September, which has increased the total capital allocation for its fleet to €34.3 million.
The NAS says €33.9 million of this is currently committed to new fleet and assets which will address the issues raised in the internal audit.
It says through the increased allocation, the National Ambulance Service has commissioned into service – 94 emergency ambulances, 10 community paramedicine vehicles, eight critical care and retrieval ambulances, and a further eight driver training vehicles in line with its replacement policy.
This policy states that National Ambulance Service vehicles should not remain in service beyond five years or 350,000 kilometres.