A controversial Kiwi mayor is being accused of bullying a group of primary school children after he sent them a letter urging them to sack their teacher.

The seven Maori children, aged between 11 and 13, had written to the mayor, Michael Laws, to express annoyance that he refused to make a spelling change to the name of the North Island town, Wanganui.

Many are campaigning to have it respelt "Whanganui", which they argue is the original Maori spelling.

But Mr Laws, a fierce critic of the name change, told them he would take their views seriously "when your class starts addressing the real issues affecting Maoridom, particularly the appalling rate of child abuse and child murder within Maori society, then I will take the rest of your views seriously".

He told them: "There are so many deficiencies of both fact and logic in your letters that I barely know where to start".

He added: "Perhaps sacking your teacher for allowing such misapprehension to flourish?"

In handwriting at the bottom of his letter, Mr Laws wrote: "PS Controlling your anger might be a start!"

The school principal, Chris Derbidge, says he decided to share the letter with the children.

"We are like a normal, mainstream New Zealand school, but we do have a Maori emersion unit. In those children's classrooms, all the curriculum delivery is in Maori. So they have been learning. So the task that their teacher had set them was to learn about letter writing," he said.

"The children had decided because the 'h' in 'Wananui' was a topical thing and a somewhat controversial thing in New Zealand at the time, so the children wrote their feelings on the matter."

Mr Derbidge says what Mr Laws wrote back was totally inappropriate.

"Most disturbing to me and to our parents and to our school community is the one that I'll read to you ... 'when your class starts addressing the real issues affecting Maoridom, particularly the appalling rate of child abuse and child murder within Maori society, then I will take the review serious'," he said.

"That is the point that we object to most strongly. They are not issues that 11 and 12-year-old children should be dealing with, or even considering."

No apology

The issue has blown up on the front pages of New Zealand newspapers, with the children saying they were upset by the response, and parents branding Mr Laws a "bully".

But the mayor, who is also a radio host and who has previously stirred up contempt by calling the late Tongan King a "bloated brown slug" - said he was "shocked" there was so much interest in his response.

He said his reply had been "facetious" but he had been genuinely shocked by the anger in the letters he'd received.

"I think it's wrong for kids to be angry about something inanimate, don't you?" he said on air.

Mr Laws said he thought the pupils were "put up to it" by their teacher.

"Do you honestly think that children give a continental about how Wanganui is spelt?"

"Children this age care about Harry Potter."

Mr Laws has not apologised, but he has invited the children to afternoon tea.

The students are not sure yet if they will accept.

- ABC/AAP