Teachers are to boycott after school activities after unions voted for industrial action over pay and workloads.

The National Union of Teachers and NASUWT said their members will take co-ordinated action short of a strike from September 26 in a dispute with the Government over pay, jobs, pensions and workloads.

The unions, which represent nine out of ten teachers, said the aim was not to affect pupils.

However members have been instructed withdraw from leading extra-curricular activities such as sports teams and drama clubs where the duties have been “imposed” on teachers. If teachers have “freely volunteered” to hold the activities they are permitted to continue with them.

The work-to-rule action will also see teachers refusing to send email outside of working hours, witholding the contents of their lesson plans from school managers and refusing to cover for absent colleagues, according to instructions sent to teachers.

They will also refuse to supervise children at lunch or invigilate GCSEs or SATs examinations, or put into practice policies drawn up by school managers unless they have been approved by NASUWT.

Thousands of teenagers are due to resit their GCSEs in November, following the row over marking boundaries this summer.

Unions said Government policies are undermining teachers’ ability to work effectively.

Chris Keates, general secretary of NASUWT, said: “The Secretary of State for Education was put on notice in May that he could address teachers’ concerns and avoid the possibility of further industrial action.

“He has recklessly disregarded this warning. At every turn, the Secretary of State shows contempt for the teaching workforce.

“What happens to teachers directly affects the quality of education for children and young people. Teachers and their pupils deserve better.”

Christine Blower, general secretary of the NUT, said: “Teachers’ morale is dangerously low. Over-the-top accountability measures are exhausting teachers and the idea that they can work to 68 is absurd.

“For the sake of teachers and children’s education, these constant attacks from Government need to stop.”

NUT deputy general-secretary Kevin Courtney said the action will be followed by strikes if the Government did not deal with teachers’ concerns.

The action from September 26 was not aimed at damaging pupils’ education, but would reduce teachers’ workloads, he insisted.

“We will keep strike action under consideration and the Government will have to move by half term at the end of October.”

The teachers pay review body will report back by the end of October on issues such as local pay, and the Government’s response will determine the unions’ next move, said Mr Courtney.

Teachers will soon start a second year of a pay freeze, followed by a 1% increase for each of the following two years.