New Zealand's teacher shortage has reached a crisis point, with principals having to resort to hiring less qualified staff or step into the classroom themselves.

The stress of a lack of teachers means Andrea Bleakley, Associate Principal at Randwick Park School, has had to return to school early.

"We've got three vacancies and it's unlikely that we're going to find anyone to fill them," she told Newshub.

"The principal said there'd been two responses."

Like most schools across the country, students will return to Randwick Park School in just two weeks - whether there's enough teachers or not.

"If we can't find a teacher to put in the classroom, then we'll have to take other teachers off support programmes," says Ms Bleakley.

It's a national problem nearing crisis level.

The Education Gazette shows 370 primary and secondary teaching positions are vacant across the country. If they're left unfilled, 10,000 students won't have a teacher.

The Post Primary Teachers' Association says the figures could be as high as 700 vacancies, affecting 17,500 students.

Schools say no students will be turned away. In some cases, class sizes will increase. In others, every effort will be made to find a temporary teacher.

"It's not a long term solution," says Ms Bleakley. "All it's doing is making the teaching profession less appealing."

The shortage is due to a lack of supply. Just 700 new teachers graduated last year - half of what the country needs.

Principals say teacher recruitment is the worst it's been for 15 years. They're going to great lengths to fill the gaps - rostering themselves on to teach, paying for moving costs, bringing teachers out of retirement and looking overseas. Some are even forced to hire less qualified people.

Whetu Cormick of the NZ Principals' Federation describes it as a teaching supply crisis.

"Five years ago at my school in Dunedin we had 120 applications for one job," he told Newshub.

"Now we're receiving between 15 and 20. But in places like Auckland, hard to staff areas, the East Coast, the West Coast for example, you're getting one or two applicants for a position.

"In fact, in some schools they're getting no applications at all."

Minister Chris Hipkins says the problem will take years to fix.

"What we can do is ensure we are doing everything we can to retain the teachers we've got now, and to bring existing teachers back into the work force."

He says any schools fearing they have a shortage should contact the Ministry.

Newshub.