Primary schools appear to be heading for a showdown with the Government over the introduction of national standards.
Principals are threatening to withhold student results from the Ministry of Education unless they get solid assurances that the information won't be made public.
From next year, the progress of primary school children in maths, reading and writing will be measured against Government-set standards.
For months, principals and teachers have insisted that the results must stay in a school's own community.
Principals Federation president Ernie Buutveld says if there are no safeguards in place, schools may refuse to send the information to a central database where it could be used to rank schools.
Education Minister Anne Tolley says the national standards will be in schools next year. However, she says she is open to suggestions on how this information should be collected and reported.
Mrs Tolley says the debate on ranking schools and league tables is a sideshow to the real issue of meeting parents' desire to bring in national standards that will help lift student achievement.
The minister says she cannot give an assurance that results will not be made public. She says schools that withhold the information would probably be acting outside the law, and she would be unable to ensure they got the extra finances and resources they needed.
The teacher's union, the NZEI, says schools will actively oppose any centralised reporting of the standards information.
It says league tables which rank schools are not in children's best interests.