The move by the Irish National Teachers' Organisation (INTO) is likely to lead to major managerial headaches for school boards, as well as leaving the Department of Education and other State agencies with a shortage of information and paperwork relating to schools.

Delegates at the INTO annual congress in Letterkenny also decided that the industrial action should involve the union's 30,000 members refusing to co-operate in other duties.

However, teachers will not be instructed to take any steps that might affect teaching and learning for pupils.

A one-day strike before 3,300 primary schools close for summer holiday, in defence of public service jobs and funding, will also be sought in conjunction with the Irish Congress of Trade Unions (ICTU) on foot of a motion passed by INTO members on Tuesday.

The Department of Education announced the embargo on promotions to posts of responsibility last month, meaning no vacancies for assistant principals or special duties posts would be filled.

The roles carry annual allowances of almost e9,000 and e4,000 respectively, with duties including co-ordination of special needs resources, compiling and returning pupil data to the department, and developing school policies in areas such as attendance and behaviour.

Around 700 such posts become vacant each year due to retirements or holders of those jobs being promoted to principal or deputy principal.

The emergency motion passed yesterday will mean that all members will be directed not to undertake those duties where a post is unfilled because of the promotion embargo, while the range of non-cooperation measures will be decided at a conference in May or June. The industrial action is also being taken in protest at the cap on teacher numbers in September 2010, at the same level as those which will be in schools next autumn, meaning a likely further increase in class sizes because an extra 10,000 pupils are expected to begin primary school next year.

Máire Ni Chuinneagáin, who became INTO president yesterday, said the union executive will direct teachers not to undertake additional duties where posts of responsibilities are not filled in schools as a result of the embargo on posts.

"The embargo on posts will affect school leadership, there are many duties and complex tasks that need to be done in schools. Government is not going to get this work done for nothing," she said.

The day of action sanctioned earlier this week at the INTO congress is part of a further series of measures, including withdrawal from modernisation measures, if teachers' pay is further frozen by the Government.

The likelihood of such a one-day strike, which the union's executive has been instructed to seek with ICTU by the end of June, will largely depend on what progress is made in social partnership talks which resume next week.