The President of the Association of Secondary Teachers in Ireland (ASTI) has said his members will be balloted on withdrawing from the Croke Park Agreement if teachers allowances are cut.
Brendan Broderick made the comments as he addressed around 450 of his members at their annual conference in Cork.
He said when his members voted for the Croke Park deal they did so "with a heavy heart", but it was seen as the least worst option.
However, he has warned that if speculation on allowance cuts proves true, the Government must "take full responsibility for the consequences".
A group of protestors from the Fightback group have held signs up during the conference showing their opposition to the cuts.
The group also heckled Education Minister Ruairi Quinn during his address to delegates.
In his speech, Minister Quinn reiterated the need to cut €77m from the education budget next year.