School secretaries at hundreds of schools stopped work for an hour this morning in a dispute over pay and conditions.
Fórsa said it represents around a third of the 3,500 school secretaries around the country and that members have been victims of an "antiquated and discriminatory" two-tier pay system since 1978.
The Department of Education has described the industrial action as premature and unwarranted.
Secretaries employed by individual school management boards can earn as little as €12,500 a year, only have non-permanent contracts with no occupational pensions, and must sign on when schools are closed.
In contrast, other secretaries directly employed by the Department of Education enjoy public servant status, along with higher pay rates, permanent contracts and pension entitlements.
While today's work stoppage and protest outside schools only continued for an hour, from now the secretaries will cease engagement with certain public service administrative systems.
They point out that if they are not paid as public servants, they will not do public service work.
Fórsa said this will affect administration in up to 1,000 schools, but will have no impact on pupils.
The department said it is currently carrying out a survey to establish the scale of the problem, and will consider the claim once costings have been established.
However, the union warns that if the dispute is not resolved, it will escalate.