One of New Zealand's top schools, Auckland Grammar, is defying the Government by becoming the first state school to dump NCEA at fifth-form level.

And nearby St Peter's College and Macleans College in Bucklands Beach are understood to be considering following suit if the move goes smoothly.

But the Education Ministry's manager of Secondary Outcomes, Tony Turnock, says that all state schools are required by law to make NCEA available to pupils who want it.

Auckland Grammar is a decile-10 state school based in the affluent Auckland suburb of Epsom. School donations are the highest of any public high school at $900 a year and it has a reputation for academic success.

This year for the first time it has directed all its fifth-form (Year 11) students to do the University of Cambridge international exams. The move was backed by the school's board of trustees and its academic committee and parents were advised in the middle of last year.

Headmaster John Morris said parents overwhelmingly supported the move. But he acknowledged "one to two people are concerned that their child couldn't cope".

Morris said the school had told fifth formers there was the "one choice", but the school could allow "some exceptions" with weaker students to have a "backup" plan and allow them to sit NCEA maths and English. There were also some NCEA level 1 subjects continuing like Latin, Japanese and Career Studies.

But he expected nearly all of the 550 students in the fifth form to sit Cambridge exams.

The move means that all students who do well in fifth-form Cambridge exams will be accepted into 6th and 7th form Cambridge studies; effectively the senior students would snub state schooling.

Morris said that the challenge of Cambridge's end-of-year exam, rather than the internal-assessment-focused NCEA, suited the learning style and nature of most boys. He has said internal assessment carried a high workload, encouraged copying and discouraged students from excelling.

Morris said: "We are confident the change is in the best interests of all our boys".

The University of Cambridge's New Zealand spokesman, Simon Higgins, said about 50 schools offered their system and he believed others were likely to follow Auckland Grammar's lead.

However, the Education Ministry said NCEA was a robust, internationally recognised qualification that set standards against which achievement in a broad range of subjects could be measured. It was designed for students of all abilities, the ministry said.

Education Minister Anne Tolley declined to be interviewed, instead releasing a written statement that she had full confidence in the NCEA qualification.

"Parents are responsible for decisions about their child's education. If they have any concerns they should contact their school."