The first Labour government in a decade is facing a wave of strike action in New Zealand, as thousands of nurses, teachers, and government staffers prepare to walk off the job.

On Monday 4,000 employees at Inland Revenue and the Ministry of Business, Innovation and Employment stopped work for two hours, demanding better pay. “This isn’t a decision our members have taken lightly, but they feel they have no choice but to take industrial action,” said Public Service Association secretary Glenn Barclay. “To put it into perspective, members at [Internal Revenue] have not taken strike action in 22 years.”

After months of negotiations, the government’s latest pay offer to nurses was rejected in June, and a nationwide, 24-hour strike is planned for Thursday. Nurses say they are overworked and underpaid, and hospitals are chronically understaffed.

Nurses have not gone on strike in New Zealand for 30 years.

Minister for health David Clark said the nurses’ discontent had been brewing after nine years of neglect under the previous, National government. “Their frustration is understandable ... I think everyone agrees nurses should be paid more than they are now, but it takes more than one pay round to address nine years of neglect.

“We have a fiscal limit, and we’ve put out there the best offer we could put out there.”

Primary school teachers have also voted overwhelmingly to strike for half a day on 15 August, their first strike action in more than 24 years.

Other groups to strike since the Labour-led government took over in October last year include cinema workers, fast-food workers, and bus drivers.

Unite union senior organiser Joe Carolan said the wave of strikes are “unprecedented”, and that workers felt emboldened under the new government and the “swing to the left”.

Carolan said concerns the strikes could destabilise the government were not justified.

“In the public sector ... some voices are saying this is not the right time to strike as we have a friendly government. So you wonder - when is the right time?” he said.

“Workers aren’t happy with 2-3% increases anymore ... I think the teachers’ demand for a 16% increase shows what the next decade of trade unionism will be like.”

The opposition National party has criticised the government for failing to listen to nurses’ concerns, and say they have a duty to meet the “hugely raised expectations” of workers under their government.

There is a fear in some quarters that the wave of strikes was affecting business confidence, which hit a seven-year low in June.

In the last significant win for unions, the New Zealand government banned zero-hour contracts in 2016, a bill supported by political parties across the spectrum.