The Ministry of Education is apologising to parents for bungling its response to children being forced into seclusion rooms at Wellington's Miramar Central School.
It comes a day after it was revealed Education Minister Hekia Parata knew for two months children were being locked in the room, before it was shut down.
"It is clear that the Ministry didn't act with the urgency it should have to stop the use of seclusion. Children's wellbeing must be at the forefront of everything we do and we will work with schools and their communities to ensure we all get this right," Acting Secretary of Education Katrina Casey said in a statement.
"We have also apologised to Minister Parata for the handling of the complaint and for a delay in informing her that the investigation had been completed."
In July, Ms Parata was told of the complaint by officials. Over the next eight weeks, the room was used 13 times before it was finally shut down in September.
Ms Casey says a series of actions have been made to improve the school's behaviour management practices.
The changes include:
Ms Parata had previously said she was only informed of the complaint 12 days ago. The Ministry says it was only on Thursday October 13 that she was advised of its investigation report.
When Newshub asked Ms Parata why the seclusion practice wasn't stopped soon after the complaint, she said it was unacceptable, and it should have been shut down.