Teachers at Merriwa and nearby Muswellbrook High School have written to the Education Minister Sarah Mitchell and Upper Hunter MP David Layzell seeking urgent assistance to address staffing.

There were currently six permanent teacher vacancies at Merriwa, a school of 30 teachers, the Teachers Federation said.

Teachers federation representative Harley Hannon is the only qualified maths teacher at the school. She said the shortages were having a "severe impact on the wellbeing and workload of executive and classroom teachers who are already overwhelmed by the daily burden of 60-hour work weeks".

"Because of the shortages at our school, teachers are having to take extra lessons, teach outside their area of, qualification and expertise; are being redeployed to cover junior classes and leaving seniors unsupervised," she said.

"Trying to teach split classes with teachers being redeployed from specialist roles is incredibly challenging. As is cancelling scheduled professional learning. Our teachers are simply burning out, while our students are missing out."

NSW Teachers Federation regional organiser Jack Galvin Waight said there was a "crisis" in NSW schools.

"Workload coupled with uncompetitive salaries are taking their toll in the Hunter and across the state with almost 3000 permanent teaching positions now vacant in NSW public schools," he said.

While numbers of vacant teaching positions vary from month to month, an internal education department "teacher dashboard" from November shows a near doubling, from 1500 in mid-2021 to almost 3000 in October 2022.

It showed 55 per cent of vacancies were in regional and rural NSW, with vacancy rates in the department's nine regions ranging from 3.89 per cent to 8.18 per cent.

Responding on February 8 to an upper house inquiry into teacher shortages, the government said classroom teachers could earn up to $113,000 a year and principals up to $200,000.

It said NSW salaries were "competitive" with other states and had risen by almost 30 per cent since 2011.

Responding to the federation's claims, Ms Mitchell said, "Labor and their union bosses are peddling a scare campaign".

"The fact is that there are currently just 35 vacancies across the 45 schools in the Upper Hunter - with 64 per cent of schools having zero vacancies and 22 per cent having just one," Ms Mitchell said.

She said more than 2100 vacancies were filled in the holidays, and NSW had 10,000 more teachers than a decade ago.

A spokesperson for Mr Layzell said he had met with the federation and the nurses' union, and had been told of a reluctance to work in the Upper Hunter.