The Irish National Teachers' Organisation says a new pension scheme for future public servants is unjust and potentially unlawful.
The INTO said it is considering a legal challenge to the scheme which is designed to save the state pension bill €1.8 billion per year.
Under the new scheme, future new entrants will have their pension calculated on a career-average basis, rather than on the basis of the final salary at the time of retirement.
Yesterday, the Minister for Public Expenditure and Reform, Brendan Howlin, said the new scheme will not significantly change entitlements for those on lower salaries.
He insisted the new scheme would be fairer and more balanced than the current system.
The General Secretary of the INTO, Sheila Nunan, has described the measures in the Bill as unfair, unnecessary and "probably unlawful".
She described government claims that the new Bill would save the government €1.8 billion as highly speculative.
