An Education Ministry survey, taken about a fortnight before the start of term, found a national shortfall of just over 500 teachers - 279 positions in primary schools and 232 in secondary schools.
A total of 300 schools were found to have one or more full-time positions unfilled and the survey suggested that 188 classrooms would be without a trained teacher at the start of the new term.
The primary teachers' union, the NZEI, says that if trained and registered teachers cannot be provided, parents should keep children at home rather have "babysitters" supervise them at school.
The ministry has rejected the proposal, which acting chief executive Lyall Perris described as "predictable scaremongering". Instead, he says, schools short of teachers can call on the ministry-funded emergency relief staffing scheme, reorganise the school or, as a last resort, use correspondence school lessons.
More primary teachers are being recruited from Australia and Britain, but the Teacher Registration Board has warned that they will need extra training. TRB figures show that of the 54 Australians who have applied for registration so far, 52 are beginning teachers with less than two years' experience and many have not had a full-time job.
The board's professional services officer, Ruth Mansell, says the one-week induction course would not be enough for beginning teachers. As well as coming to grips with the curriculum, they will have to understand the obligations to bi-culturalism required by the Treaty of Waitangi.