Twenty-two students have been withdrawn from a Whanganui school this year following complaints about bullying by a teacher.

And caregivers say there are another 17 pupils who may not return to Kaitoke School next year because they are dissatisfied with how the school has handled the bullying complaint.

The Ministry of Education says it has received a complaint about one teacher's treatment of students and it is helping the school board of trustees manage the issue.

The school — which usually has a roll of about 110 — has so far not responded to requests for comment, but the Whanganui Chronicle understands the teacher in question is still at the school.

The Chronicle has seen documents confirming the school board brought in an independent investigator to look into complaints. It is not known what the outcome of the investigation was.

The woman who laid complaints against the teacher with the ministry, police and the school was a caregiver of one of the students and she has since taken him to another school.

"The police have finished their investigation, the file remains open but they were unable to prosecute," she said.

"It now is in the hands of the education complaints authority."

Students who have been removed have gone to a range of schools such as Whangaehu School, Whanganui Intermediate School, Aberfeldy School and Carlton School.

As well as the allegations of bullying, some parents and caregivers have been frustrated one of the teachers had her one-year-old toddler with her in the classroom for two hours a day.

There are now just 10 students left in that classroom.

Parents have also complained their concerns have fallen on deaf ears with the board.

"It's in crisis — 22 students vacating the school in eight months of this year," said a grandparent who has withdrawn his grandchildren from the school.

"There's been an issue with the baby in the class, and there's been an issue with ... anti-social behaviour by a teacher, which has never been addressed.

"People had to go to police. Police haven't got enough evidence to prosecute, so it's a case of whether it's been resolved or put on hold."

The bullying was so bad, according to the grandparent, that it became difficult to keep his grandson calm on Sunday nights. A doctor gave his grandson a week's leave because of stress.

"On a Sunday night we would end up going over to my daughter's to try and get him to go to bed. He wouldn't go to bed because ... when he woke up he'd have to go to school. And it was a hell of a chore."

His grandson was now doing well at another school and was showing that he wanted to be there, he said.

The grandparent was concerned the teacher in question was still at Kaitoke School.

School principal Vanessa Bourne, acting deputy principal Antoinette Mayo, and the acting chairman of the board Rob Crawley have all been approached for comment.