An independent inquiry should immediately investigate the use of "time out" rooms in schools, says the head of the national autism charity.
Dane Dougan, chief executive of Autism New Zealand, said the agency had been flooded with calls from worried parents following news that children at a Wellington primary school had been locked in a dark, cupboard-sized room as punishment.
The Herald revealed an 11-year-old autistic boy had been shut in the room at Miramar Central School 13 times in nine days, and was discovered by his behaviour therapist crying out "I'll be good I'll be good".
His mother says he is still traumatised and she plans to lay a complaint with the Ombudsman and police.
Following the story, the Ministry of Education said it was aware of other such rooms around the country, but did not have an exhaustive list, or a record of when they were used.
Dougan said that in itself was problematic.
"We need to know where else this is happening. How often? Is it a widespread problem? And if it is we need to educate schools that there is a better way of dealing with autistic kids," he said.
"Locking anyone away in a dark room is a terrible situation."
He said the government should request an independent agency to undertake an inquiry.
Green education spokeswoman Catherine Delahunty backed the call, but felt it was unlikely the Government would agree.
"But we need answers on the practice as soon as possible, so some kind of investigation is essential," she said.
The Herald has since been told of at least three other rooms around the country, but is yet to confirm if they are still in use.
Yesterday, a group of parents with disabled children wrote an open letter to Government asking the practice be made illegal.
"It is a cruel, outdated and traumatising punishment that we call on to cease immediately if it is being used elsewhere in any New Zealand school," the letter said.
"The staff who locked these children in this room need to be held to account, along with anybody in authority who sanctioned this practice."
A Ministry of Education investigation found reasons children were put in the room included hitting, making a mess, disobedience, and a lack of focus.
It said while staff had best intentions, the practice was "outmoded". The ministry strongly recommended the school stop using the room.
Principal John Taylor-Smith said it will phase its use out.
It was the second such incident in New Zealand schools in recent months - the first, when a 13-year-old boy attending a special school was put in a time-out room last year - prompted the development of soon-to-be released seclusion and restraint guidelines.
A spokeswoman for the Office of the Children's Commissioner said it was also concerned, and would be talking with relevant agencies to work out whether it was a wider systemic issue.
Labour's education spokesman Chris Hipkins said the Ministry of Education should fully review the situation and produce clear guidelines for schools.
"It's not a practice that I'm personally comfortable with and not one I imagine parents will be comfortable with either. I don't think a full inquiry is needed, this is a core responsibility of the Ministry of Education."