Education Minister Hekia Parata is blaming her department for the release of inaccurate information about the number of teachers.
Ms Parata told Parliament recently that the number had risen by 15 percent under the National-led Government.
She clarified her earlier comments today, saying the number of teachers has actually increased by 6.5 percent.
The secondary school teachers' union had criticised her for citing the figure of 15 percent, saying she should have checked her facts first.
Officials say the error arose because the Ministry of Education used data that included part-time and relief teachers from the Novopay payroll system, whereas earlier data had not included those groups.
Ms Parata said the ministry has apologised.