An investigation has been launched after a special needs child was allegedly put in a two-metre by two-metre, cage-like structure made of pool fencing at a Canberra public school.

Education Minister Joy Burch said between March 10 and March 27 the child was placed in a "withdrawal space" inside the classroom.

It is understood the incident involved a 10-year-old boy with autism.

Words could not describe her disappointment and horror at the situation, Ms Burch said.

"This structure could not be deemed acceptable in any way shape or form, in any of our public education schools, hence it was withdrawn," she said.

"I have initiated an absolute thorough investigation as to the why and where ... this structure was allowed to be put in place.

"I have also made assurances through the school executive and through our support teams that the child and the family involved is given the utmost support over this time."

The school principal has been stood aside, but the name of the school cannot be revealed for privacy reasons.

The issue emerged last week after a complaint was made to the Children and Young People's Commissioner.

Parents with students at the school have been informed of the incident.

Ms Burch said the student remained at the school and two extra staff had since been assigned.

'This is not how our students should be treated'

Diane Joseph from the ACT Education Directorate said it was an isolated example of very poor decision making.

"The space was basically a fenced-in structure inside a classroom," she said.

"It was entirely inappropriate and unacceptable, and the structure has been removed.

"The decision to erect such a structure raises so many questions.

"This is not how our students should be treated."

The withdrawal space was built for a particular student, but the directorate conceded it did not know if it had been used for other students.

The Minister said an investigation would be conducted in two streams with the first stage expected to be completed within weeks.

It would be led by someone independent of the ACT Education and Training Directorate.

Independent inquiry needed 'without delay'

Hugh Boulter from the ACT public school Parents and Citizens Association said he was most alarmed at the news and has called for a speedy, independent inquiry.

Hugh Boulter from the ACT P and C Association was alarmed by news of a cage being used at a public school. ( ABC News )

"At this stage on behalf of the P and C Council and ACT parents I would call for an independent inquiry to be conducted without delay," he said.

"I would also ask that it is important not to speculate until the findings of the independent inquiry are handed down and fully evaluated to ensure natural justice.

"I'd also call for the directorate to make inquiries in to non-government schools as well, immediately, to remove any question of systemic performance in the ACT."

Liberal ACT MLA Steve Doszpot was horrified by what he had heard so far about the case and said many questions remained unanswered.

"Have these sort of situations occurred before? And do we have any other structures like this in other schools? Why has it taken so long for the issue to be escalated?" he said.

"I understand that the Directorate knew about this last Thursday, and it is now a week later.

"So these are questions that remain to be answered and an inquiry is the very least that should happen."

Meanwhile, the Federal Assistant Social Services Minister Mitch Fifield expressed his concern over the incident on ABC's Radio National.

"It's appalling what we've heard from the ACT," he said.

"Regrettably, we do hear of instances around Australia in schools from time to time where there are inappropriate restrictive practices used.

"This is something that we need to look at, not just in schools, but also as we look to the roll out of the National Disability Insurance Scheme (NDIS) nationwide."

Senator Fifield said the roll-out of the NDIS would improve safeguards for people with disabilities, and help implement uniform national complaint practices.

Ms Burch has appealed for the media to consider the privacy of the family involved.