The National Union of Teachers (NUT) has sent out ballot papers to its 175,000 members in England and Wales on the issue of a proposed boycott of a new appraisal system.

The new system is a key element of ministers' plans to reward teachers for their performance, including how well their pupils fare in national tests and exams.

Doug McAvoy: "Payment by results is not supportive of professional teamwork"

But the NUT is implacably opposed to any form of performance pay for teachers.

Its General Secretary, Doug McAvoy, said the government had to be prepared to change its approach.

Minor concessions - such as the recently announced delay in implementing changes to the appraisal system - would not halt indutrial action by the union.

"The government has refused to recognise the damage that will be done to our schools by its proposals," said Mr McAvoy.

"Schools depend on teachers being willing to share good ideas and resources, to work in partnership with colleagues, and to provide advice and support to colleagues in difficulty.

"Pitting teacher aginst teacher will lead to the destruction of that co-operation."

The decision to ballot members on industrial action was taken three weeks ago at the NUT's annual conference in Brighton. Ballot papers must be returned by Friday 7 May.