A primary school allegedly locked an autistic student inside a cage, prompting the ACT government to launch an investigation.

Education Minister Joy Burch made the shocking claim on Thursday afternoon, saying the special needs child was 10 years old at the time.

The cage was reportedly constructed with pool fencing, measured two metres by two metres and was erected inside a classroom.

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Words could not describe her disappointment and horror, 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structure could not be deemed acceptable in any way shape or form, in any of our public education schools, hence it was withdrawn,” the Minister said at a press conference.

“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 has reportedly stood aside its principal and appointed two extra staff, while the student remains enrolled.

The Human Rights Commission alerted the state government to the allegation after a complaint from the child’s family.

ACT Education Directorate’s Diane Joseph said the decision to erect the structure “raises so many questions”.

“This is not how our students should be treated,” Ms Joseph said.

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

The government-instigated investigation into the incident will be headed by an independent person.

It is not yet known if the fence-like structure was ever used to constrain other students.

The school is yet to be named.