Christchurch Girls High School board of trustees has defended its decision to sack the principal, saying there had been tensions between the board the Prue Taylor since 2009.
Ms Taylor was dismissed from the position at the school on Friday, after 13 years as principal.
In a statement posted on the school's website on Monday and read to students at an assembly, the board said it had been working to resolve issues of concern since 2009.
The statement said the seriousness of the issues and tensions were highlighted in a recent ERO report, which has been publicly available since August.
Ms Taylor has indicated she will fight the dismissal.