A college in Tauranga had to withdraw the NCEA results of 17 students after the Qualifications Authority found a teacher gave them the answers to internal assessments.
The case was in Qualifications Authority documents obtained under the Official Information Act by Radio New Zealand News.
NZQA was called in after Otumoetai College spotted problems with the work of students studying Maori at levels two and three of the NCEA late last year.
Principal Dave Randell says NZQA later found the teacher had been giving students the answers for internal assessments.
The teacher was the subject of competency action, which he successfully completed.
However, 17 students lost credits for Maori standards the teacher said they had achieved and five missed out on level three of the NCEA.
Mr Randell says the teacher was naive and just wanted to help the pupils.