Acting Prime Minister Winston Peter has called news primary school teachers will extend a planned strike to a full day "hugely disappointing" and asked for time to settle their claims.
"They give us a chance we'll help them into the future, we can't do it all in the first year. They know that and so it's a serious disappointment," he told The AM Show.
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Mr Peters said he understands the difficulties teachers face, but striking isn't going to fix the issue.
"We're still negotiating with them, there's some sort of belief out there that it will help the negotiations by striking, well it won't," he said.
"I'm sorry to say that, we've got to carry on negotiating until we get to a resolution, but striking and putting a whole lot of parents and children at enormous difficulty is not the best idea."
Primary school teachers have voted in favour of taking a full day of strike action in August.
The new full day strike replaces the previously planned three-hour walk out on August 15. It's been 24 years since primary teachers have taken action.
Teachers were offered a pay rise over three years from the Ministry of Education, but votes taken at paid union meetings in June showed the majority opted to reject it.
The offered pay rise ranged from 6.1 percent for the top of the pay scale, which would have made the maximum teacher's salary about $80,600, to a 14.7 percent increase to the entry salary, bringing that to $55,030.
The New Zealand Education Initiative (NZEI) says 86 percent of teachers have been offered a pay increase of just 2.2 to 2.6 percent a year for three years.
A spokesperson for the NZEI said there is now no opposition to providing better pay for teachers.
"The National Party's u-turn on teacher pay and new desire for smaller class sizes means there is now no political opposition to addressing the crisis in education," said lead teacher negotiator Liam Rutherford.
"The members' decision to take industrial action shows the degree of frustration and conviction among teachers and principals."
Lead principal negotiator Louise Green said the union was clearly in favour of moving to a full day strike.
"A clear majority of both member groups voted in favour of a full day, giving a strong endorsement for collective action," she said.