Many schools are illegally stopping children from attending class, saying they don't have the specialist support to deal with their behaviour, Disability advocacy group IHC and the Green Party say.
The Ministry of Education was today trying to resolve a situation in the town of Paeroa where local schools won't accept a boy without more help to manage his aggression.
The nine-year-old was suspended from Miller Avenue School last year and was supposed to return to class in late February.
That had not happened by mid-April and the ministry said it was working with local schools to get the boy back into education.
The ministry's head of sector enablement and support, Katrina Casey, said it did not have any evidence that such cases were common.
"There are from time to time students who present with very challenging behaviour. These are exceptional cases, and when they happen we work hard to resolve them with both the school and family of the student involved," she said.
But IHC director of advocacy Trish Grant said a survey it conducted last year revealed that it was common for schools to refuse or limit a child's attendance.
"Seventy percent of the families and around the same percentage of school professionals were saying that this was a common experience," she said.
Both groups of respondents agreed schools did not have access to the specialist support they needed to look after the children in question.
Preventing children from attending school was not fair, she said.
"What then happens is that this child is demonised, this child is perceived as too bad to be in school, when in fact all children have a right to education."
Green Party education spokesperson Catherine Delahunty said she had listened to hundreds of submissions to the Education and Science Select Committee's inquiry into autism and dyslexia in schools.
It was hard to quantify the scale of the problem, but it was clear from the submissions that the Paeroa case was not isolated, she said.
"There were a number that made reference to their child having been excluded or effectively excluded at some time because there was insufficient support."
Educational Institute president Louise Green said sometimes principals felt that sending a child home was the only option.
"If the school's put in every resource it can and it's accessed every funding resource it can, then actually what do you do? Because you also have to maintain a safe environment for the other children and staff and you want the child at school to be actually in a good place to be learning."
The special education system was under-resourced, but the ministry usually provided the extra help schools needed for extreme cases, Ms Green said.
Ms Casey said schools should talk to the ministry if they were concerned about the level of support a child required.
The ministry would intervene if children were denied their right to an education, she said.
"We will take up any cases for parents where a school is not welcoming of their child, as no school is legally entitled to turn away a student with a disability or special educational need. In those cases we work to ensure the child continues to receive an education whilst we find a school for them. We never give up on any child, and every child has the right to an education."