A significant proportion of public service jobs require third level, specialised and/or technical qualifications, according to the report of the benchmarking body.
Nearly half of public sector employment (48 per cent) is taken up by professional, associate professional and technical groups, compared to only 12 per cent in the private sector, it found.
Natural wastage, together with the rapid expansion of some services, had created shortages which the labour market is unable to meet, according to the report.
Since 1987, both public service and private sector pay have been largely determined by collective bargaining within the framework of the national wage agreements.
Centralised collective bargaining was a necessity in the public service, the body concluded, given the complex relationships between a large number of diverse grades where local bargaining was not feasible.
The report recognised that the emergence of shortages from time to time in specialised "hot skills" functional areas in both the public and private sectors posed problems for recruiters. But these were often cyclical in nature or were caused by "exceptional circumstances".
Private sector responses to such developments were characterised by flexible and temporary pay arrangements, including "often atypical employment regimes which cease at the end of the period of skills deficiency".
It was not appropriate to make permanent adjustments to longer-term pay and career-based employment regimes in the public service to resolve such temporary supply problems, said the report.