Around 3,000 civil and public servants in Northern Ireland have voted overwhelmingly to strike over cuts to their jobs, pensions and pay.
The coalition Government is now facing the biggest outbreak of industrial action since it came to power.
The Northern Irish workers were included in a UK-wide ballot of more than 250,000 Public and Commercial Services (PCS) union members.
Members voted by 61.1% in favour of strikes, and by 83.6% for other forms of industrial action, on a turnout of 32.4%. It has also emerged that prison officers are to stage lunchtime protest meetings in Northern Ireland.
Up to 750,000 public sector workers across the UK are expected to stage a 24-hour walkout on June 30, with civil servants then embarking on a month-long ban on overtime.
The action could spread later in the year to other parts of the public sector, including councils and the NHS, threatening an autumn of discontent involving more than 1.5m workers.
PCS’s Ireland regional committee chairman Barney Lawn said: “Both Westminster and the Northern Ireland Assembly need to listen to this ballot result.”
The Prison Officers Association said later that every prison and secure hospital POA branch in England, Wales, Scotland and Northern Ireland will hold meetings on June 30 during lunchtime.
Steve Gillan, general secretary of the POA, stated: “The membership will show solidarity with a protest meeting with other trades unions, to demonstrate our opposition at these needless changes.”
The news followed huge strike votes yesterday by members of the National Union of Teachers and the Association of Teachers and Lecturers over pensions.
More than 300,000 teachers were balloted in total, and the walkout is set to be the biggest day of action by teachers in decades.
Prime Minister David Cameron's official spokesman said that the Government wanted “an open and constructive dialogue” with unions.