Canterbury schools were fed "inaccurate and insufficient information" around closures and mergers after the 2011 earthquake, the Chief Ombudsman has found.
Chief Ombudsman Peter Boshier's report, called Disclosure, was released on Wednesday.
His investigation found that the process of merging and closing schools was mismanaged, "adding stress to already traumatised communities", and resulted in a major loss of trust between the Canterbury public and the Ministry.
He said the Ministry faced "unprecedented challenges" in the Canterbury region after the earthquake but was hindered by a lack of any established process for even small-scale school reorganisations.
It was announced in September 2012 that 13 schools would close and 18 others would be merged, shocking the school community, who expected better engagement and transparency before decisions were made.
"Essentially, while schools and communities were engaging in what they thought was a genuine discussion about broad future visions for schooling in Canterbury, the Ministry was progressing a business case with detailed plans for individual schools," Mr Boshier said.
When the plans did come out, the announcements were "poorly handled... with inaccurate and insufficient information provided," he said.
Mr Boshier recommended public apologies through local media and, in future, much closer work between the Ministry and schools around the process for closing or merging.
The Ministry has accepted Mr Boshier's recommendations, with deputy state services commissioner Debbie Power saying "things should have been handled differently".
"The Ministry has made a number of changes since 2012, including to its engagement process to make sure it is better prepared for any future closure or merger processes," she said.
"It is currently working with school leaders on further improvements to this process."