School leaders say they do not believe the Government's estimate that half of all state and integrated schools will gain teachers under new staffing ratios in 2013.
They say they know of no primary or intermediate school that will be better off and want the Ministry of Education to provide school-by-school forecasts as soon as possible.
Primary and intermediate school leaders say they are surprised by the Government's calculation, because schools have been estimating their likely staffing and none have said they will be better off next year.
They say schools can not wait until September to find out their staffing entitlement for 2013 and want the ministry to provide estimates now.
They fear the ministry is holding back its figures because they will scare schools and warn that even with more teachers, the new staffing ratios will mean bigger classes at many schools.
The Ministry of Education has rebuffed requests from Radio New Zealand News for its estimate of staffing levels.
It has also told the Post Primary Teachers Association it must ask for forecast enrolment numbers through the Official Information Act - even though they have been readily available in the past.
PPTA president Robin Duff says the ministry appears to be withholding the information because it will terrify schools.
Union says 2000 schools will lose teachers
New estimates show more than 2000 schools will lose teachers unless their rolls grow before the Government's new staffing ratios take effect next year.
The calculations by the PPTA show that 83% of all 2400 state and integrated schools schools stand to lose funding for teachers.
The union says those at risk include all but one primary school and all area schools. But it says two-thirds of secondary schools might gain staff.
The PPTA says the actual outcome for schools will depend on enrolments. Primary school rolls are expected to rise slightly next year while secondary school rolls fall.