Members of the Defence Forces are being forced to retire as young as 30 because a promotion embargo is blocking progress through the ranks, it has been claimed.
The PDForra association said since 1994 soldiers who enlist as a private must quit after 12 years service unless they advance to the rank of corporal.
It added that corporals are forced to leave the military after 21 years of service, normally at the age of 39, unless they progress to sergeant or a higher rank.
However, Simon Devereux, PDForra deputy general secretary, said a two-year embargo on promotion has prevented members of the army, navy and air corps from moving up the ranks.
"Prior to 1994 there was a concern about the age profile in the Defence Forces and why there was a number of people in the rank of private at a very high age," he said. "In order to eliminate that problem and encourage progression, the criteria was brought in that they have to be in a particular rank by a particular time. But when that contract was drawn up it was never envisaged there would be no promotions because of the public finances."
PDForra, which represents staff soldiers, seamen and airmen, called on the Department of Defence to review the terms of service for all personnel by setting retirement at 31 years service for all private soldiers, corporals and sergeants - as well as their equivalents in the Air Corps and the Naval Service. Both sides are expected to enter into negotiations later this week.
"It makes no practical sense to dismiss personnel on reaching 21 years service," added Mr Devereux. "Many of these people will be at their very peak in terms of output - and large numbers will be technically qualified, after years of training and very specific skills development. The Defence Forces will have invested a lot of money in these people.
"Our most critical work is peace keeping, where experience and training are key issues across a range of specialities."
The Department of Defence said like all sections of the public service the permanent Defence Forces are subject to a promotion and recruitment moratorium. However it confirmed a claim received from PDforra in relation to personnel enlisted after 1994 was being dealt with confidentially under the Conciliation and Arbitration Scheme.
Defence Minister Alan Shatter said: "Due to the robust nature of many military operations and their attendant physical training regimes, personnel are exposed to a unique range of challenging environments. In these circumstances it is vital that the age and health profile of personnel be such as to ensure that operational capability and effectiveness are not compromised."