The Irish National Teachers' Organisation, which represents the country's primary school teachers, is to participate in the new public service pay agreement, even though 89% of its membership rejected it in a ballot held last July.
The INTO executive had recommended that its 32,000 members oppose the new agreement, because it failed to eliminate the two-tier pay system under which teachers recruited after 2012 were paid 10% less.
However, at a meeting yesterday the union's leadership decided to not repudiate the new deal, called the Public Service Stability Agreement.
In a statement published on its website, the INTO's executive said: "In a context where the PSSA has been accepted by a large majority of public service workers and where the review of pay equality issues will commence in October 2017, the CEC decided that it is in the best interest of members, and in particular of post-January 2011 entrants, that INTO participate and actively represent members in the reviews of both pay equality and of the outstanding Principals' award. That because the PSSA has been accepted by a large majority of other public service workers, and where a review of pay equality issues will begin in October, it has decided that it is in the best interests of its members to become part of it."
In a further statement today, INTO said: "The Central Executive Committee of the INTO met yesterday (Friday 22 September).
"At the meeting it was decided to participate in the review of pay equality which will begin next month, a year ahead of what had been originally agreed.
"This was the only decision made at the meeting and it followed the union's call for an early engagement on the issue of pay equality.
"The Executive did not make any decision in respect of the Public Service Stability Agreement, 2018-2020 which members overwhelmingly rejected earlier this year."
When members rejected the deal in July, INTO General Secretary Sheila Nunan said the result showed clearly that the terms of the agreement were unacceptable to the vast majority of primary teachers.
She said that while progress had been made in recent years on pay equality, this was not continued in the recent pay talks.
Ms Nunan is the current president of the Irish Congress of Trade Unions.