Headteachers are using new rules for managing teacher performance to “intimidate” and unfairly discipline experienced and highly paid members of staff, one of the main classroom unions has claimed.

Changes to capability proceedings - which are designed to deal with underperforming staff - have led to a “climate of fear in too many schools”, with women and long-serving teachers particularly affected by the reforms, delegates at the NASUWT conference heard.

The way teachers are appraised each year was overhauled last September in a bid to speed up the process under which weak teachers can be forced out of the classroom. Capability proceedings, which previously lasted around 20 weeks, are now supposed to be completed in four to 10 weeks. The limit of three hours of formal classroom observation a year was scrapped as part of the reforms, while a new set of standards was introduced against which teachers are appraised.

But concerns have been raised that the system is being abused, with Chris Keates, general secretary of the NASUWT, saying that heads are taking advantage of it “just because a teacher’s face doesn’t fit”.

“There is a climate of fear in too many schools, with capability procedures being used to intimidate staff,” she said in response to the debate at the union’s annual conference in Bournemouth.

Kathy Wallis, a union executive member, said casework on the issue had increased by 22 per cent in Cornwall between 2010 and 2012, as teachers fought against what they saw as unfair judgements on their performance. In Torbay, the number of cases of teachers involved in capability proceedings who had also suffered from health problems had increased from three to 17 during the same period, she said.

Ms Wallis said the situation was “ruining” the lives of teachers and their families, with experienced staff being hit as schools attempted to save money. “Those who are expensive to pay are being targeted,” she said.

Richard Featherstone, from Middlesbrough, said older members who were in their mid-fifties, women and those who worked in primary schools were particularly affected by the changes and were being put through capability proceedings “with very little evidence”.

“One observation could be enough,” he said. “Then you get on to the railway track and it is very hard to get off.”

Mr Featherstone said the process was supposed to be supportive, but facing more observations made the teachers feel stressed and was counterproductive. “Many of these teachers are on #163;34,000 to #163;35,000,” he added. “Who are they replaced by? Someone who will earn #163;25,000. Somehow the head pockets an extra #163;10,000 for whatever vanity projects he has for the school.”

The introduction of new capability proceedings was heralded by the government as giving school leaders the power they needed to address poor performance. “Underperforming teachers place additional pressures on their colleagues and let down the children in their care,” a Department for Education statement said.

The issue was also debated at the NUT conference. General secretary Christine Blower said the reforms were “unnecessary and punitive, have nothing to do with standards and if adopted only serve to demotivate teachers”.

But Russell Hobby, general secretary of heads’ union the NAHT, said it was “too soon” to make judgements about the system, and said school leaders did not base decisions on teacher performance based on whether they liked the person or not. “The vast majority of heads want to behave properly and do the right thing. They just want good teachers and a constructive atmosphere in their school, where people know they can develop their career.

“The best teachers are often long-serving so they are keen to keep them. Heads have to manage carefully the quality of teaching ... and capability proceedings should be a last resort.”

AGE CONCERN

Between 2008 and 2010, the NASUWT provided professional casework support for 773 teachers in the UK in relation to capability and competence issues.

Union statistics suggest that capability and competence proceedings are used disproportionately for older teachers.

A total of 46 per cent of cases involved people aged over 50, but this group represents 32 per cent of the UK teacher workforce and 19 per cent of the NASUWT membership.