Rules that will force the first batch of Defence Forces troops to retire next year while still as young as in their late 30s were introduced to ensure the military was physically fit and adaptable, Minister for Defence Simon Coveney has said.

He insisted those who will be forced out will be “looked after”, but said the reality was they had already benefitted from generous extensions to their initial five-year contracts. Younger men and women were needed for robust foreign deployments, he added.

The Government is coming under pressure, including from Minister of State Ann Phelan TD (Lab), to relax a rule introduced in 1994 that stipulates personnel who have not risen to the rank of sergeant must retire after 21 years’ service.

“These are front-line troops who get exposed to the most robust demands of military life at home and abroad, often in conflict zones,” Mr Coveney said of the privates and corporals who will be forced out from next April.

He cited the current deployment of Irish troops to a United Nations monitoring mission on the Golan Heights in Syria, where they had to manage cross-fire between warring factions.

“This is dangerous work; these are soldiers who’ve been trained for a military life.

“We need to ensure that they’re fit, they’re strong and they’re adaptable. And that their safety and the safety of the soldiers around them is protected. Back in 1994, the decision to reduce the age profile was made for all of those reasons.”

The recruits who entered in 1994 were on five-year contracts from the outset, which were increased to 12 years under renegotiation three years later. In 2004, further negotiations allowed them serve for up to 21 years, unless they were promoted to the rank of sergeant, at which stage they could stay on until aged 50.

The association representing about 8,000 soldiers, sailors and aircrew of the Defence Forces, PDforra, said it and the Government would make submissions to a public service adjudicator in coming months. That office holder would make a decision on the association’s request for personnel who could demonstrate they were fit and healthy to serve until aged 50.

PDforra general secretary Gerry Rooney said most of the personnel set to be forced out are now married with children and were still paying off mortgages, some with many years left to run, and also with childcare to pay.

“They are in that period in family life when there is the greatest demand on a family’s budget. It makes it extremely difficult.”

He added the general levels of health and fitness are much better among personnel than in the mid-1990s, when the measure was introduced.

Societal lifestyle changes and the shift in the way the Defence Forces had approached the health and fitness of its members had ensured both were better now than in previous generations.

Ms Phelan said she was concerned about the measure because, in future years, those forced out would face a long delay waiting for their gratuity payments and pensions.

“I am just looking for a flexibility with some of the Defence Forces, that people look at where there is a very severe impact on their life if this happens, that they are given some level of second chance perhaps to be able to meet the criteria (to continue serving). I’d like a level playing pitch for these people.”

Those who joined the Defence Forces between 1994 and 2004 who are forced to leave after 21 years will receive pensions and gratuity payments immediately.

However, for those who joined after 2004, when their time comes to leave they will be as young as 38 years and will receive neither gratuity nor pension until reaching the age of 60 years.