The Association of Secondary Teachers in Ireland (ASTI) has stated that its executive was "too busy" to issue an invitation to Education Minister Jan O'Sullivan to attend its annual conference.
The union has been locked in a bitter dispute over the issue of Junior Cycle Reform, which has seen two days of strike already, with further work stoppages not being ruled out.
ASTI general secretary Pat King is insisting the lack of an invitation for Jan O'Sullivan to attend the gathering at Easter is not a slight.
"The issue of inviting the Minister wasn't revisited by our executive, so the minister hasn't been invited to the conference," he said.
"It's certainly not a slight, we would never seek to offend or slight any Government Minister or any politician for that matter.
"Just no decision was taken on inviting the Minister and the Minister hasn't been invited."