TEACHERS at Catholic schools involved in a pay dispute have voted overwhelmingly in favour of strike action.
Members of the Irish National Teachers' Organisation (INTO) will walk out on January 18 and the union is warning of further stoppages.
School closures, the union warned, were now unavoidable.
The largest teaching union in Ireland, it has about 7,000 members in the north, most of them in Catholic maintained schools.
Members are angry, having rejected a pay offer that would see teachers receive no pay rise for 2015/16, and a 1 per cent cost of living uplift for 2016/17.
Education minister Peter Weir has said he is disappointed by the "futile" industrial action adding that pay negotiations are over. He said unions rejected a two year pay deal, which was would have seen an increase of 2.61 per cent to teachers' pay.
Already, teachers in another union - the NASUWT - have had a one-day strike with more action planned next year.
The INTO ballot revealed that half-day strike action was supported by 78 per cent of INTO members with almost 95 per cent voting in favour of action short of strike.
Seamus Hanna, chairman of the INTO northern committee, said the union had taken every possible measure to talk to those in power and agree a deal "which is right and just".
He said teachers' goodwill and professionalism "will no longer be allowed to be taken for granted".
"The INTO has taken every possible measure to avoid the closure of schools," he said.
"We constructively entered into talks to find a just and reasonable pay deal but this was met with an imposed award which provides no salary increase for teachers for the year 2015/16 and an imposed 1 per cent for 2016/17. Teachers remain the only group within education to be denied any increase for 2015/16.
"Despite the sincerity of our efforts all attempts to find a just settlement and avoid the closure of schools have now failed."
Action short of strike will commence on January 6 and will involve INTO members withdrawing all cooperation with inspectors. This will be followed up with a series of half day strikes - the first of which will take place on January 18, with future dates to be confirmed.
Northern secretary Gerry Murphy said the action was aimed at securing a just and fair pay settlement for members.
"We will continue to remain available to engage meaningfully with the education employing authorities and the minister. The ball is in their court," Mr Murphy said.
Meanwhile, the Association of Teachers and Lecturers union has agreed to take action short of strike, which will include non co-operation with inspectors.
