Secondary school teachers have overwhelmingly supported a vote for industrial action on different pay scales which they say are undermining the profession.

The annual convention of the Association of Secondary Teachers of Ireland (ASTI) on Tuesday heard that teachers who entered the profession after January 2011 face pay gaps of up to €9,000, or about 20 per cent.

Almost all the 400 delegates voted to ballot members on industrial action, up to and including strike action, if the issue is not resolved by a deadline of August 31st.

Declan McInerney, a member of the union’s Wicklow branch, said pay inequality was “driving a wedge” between member and amounted to “blatant discrimination.”

“We need to make restoration of single basic pay scale a priority for the union over the coming years,” he said.

Michael Browne, a member of ASTI's Bray branch, said the pay gap was unacceptable and would have far-reaching consequences for the sector unless it was tackled soon.

“It will become increasingly difficult to attract new entrants to the teaching profession . Just look at what is happening in the UK,” he said,

Speaking after the vote, Kieran Christie, the ASTI's general secretary, said the union was acting responsibly by sending a signal to the next minister for education that there was a window of opportunity to avoid industrial action.

He said the form of this action had not been decided, but he believed there was a chance to resolve the issue over the coming months.

A spokesman for acting Minister for Education Jan O’Sullivan said the Government was committed to addressing public sector pay by negotiation rather than by diktat.

He said the Lansdowne Road pay agreement has begun the process of restoring the reductions to public sector pay which have been implemented over recent years and provided three flat-rate increases to teachers salaries.

“Flat rate increases are more favourable to those who are lower on the pay scale than percentage increases would have been, and are therefore more favourable to new entrants to the teaching profession than to longer serving teachers,” he said.

At the convention, Ed Byrne, president-elect of the ASTI, said the it was important to point out that unions had no hand, act or part in the "heinous disparity" which has been foisted upon them by successive governments.

“That the the Department of Education should stand over a policy that is not only discriminatory but anti-educationalist puts it in state of shame,” he said.

A number of newly-qualified teachers told the convention that the issue has not been dealt with sufficiently seriously by the union over recent years.

Unless demands were followed up by industrial action, they said the next Government will not listen.

The ASTI’ s president Máire Ní Chiarba said the treatment of newly-qualified teachers was one of the main reasons for its rejection of the Lansdowne Road pay agreement.

“The agreement did nothing to address the totally unacceptable situation for new entrants,” she said.

“Had we accepted it, the message would have been: it’s perfectly acceptable to discriminate against specifically targeted groups of teachers. Well, it is not acceptable to indulge in such discrimination. As a trade union we will continue to pursue this discrimination until it is reversed.”

She also said the “culture of casualisation” was a shameful and unacceptable situation which was causing instability in the lives of many teachers.

Ms Ní Chiarba said some teachers were paid as few as four teaching hours a week.

It was ironic that the Department seemed to be concerned about improving teaching and learning give the instability and discontinuity caused by low hours.