The education secretary has reacted angrily to the latest strike threat from a teaching union.

On Friday the country's biggest teachers' body, the NUT, said a survey of its members showed overwhelming support for industrial in protest at tests for seven, 11 and 14 year-olds.

However Charles Clarke condemned the proposal, describing it as an "absolute betrayal" of pupils and parents.

A poll showed 82.5 per cent of NUT members wanted to boycott national curriculum tests for seven-year-olds, with 71.4 per cent saying the same for 11-year-olds and 64 per cent for 14-year-olds.

An NUT boycott would cause nearly all schools to have to scrap the tests, which the government believes are an essential means of measuring performance.

Following the results of the survey of 30,000 members, the NUT executive is now likely to initiate a full ballot on strike action.

General secretary Doug McAvoy said the tests were an extra layer of bureaucracy and an unfair burden on teachers and students.

"The government would be hard put to find a teacher who thinks they are beneficial, improve achievement or promote a broad and balanced education for our children," he said.

"They narrow education, limit use of professional judgment, place unnecessary stress on pupils and add significantly to the workload of teachers without producing any benefits.

"The strength of union members' views is undoubtedly replicated across the profession.

"The government should end the tests and free teachers to use teacher assessment to determine pupils' needs and inform parents of pupil progress."

But Clarke responded by defending the tests and slamming the union for threatening strike action.

"Testing is a fundamental part of raising standards in schools. They help teachers see what progress their pupils are making," he said.

"The national tests are particularly important for children in the most disadvantaged areas.

"Testing tackles the low expectation culture that used to hold back those children [and] parents value the information testing provides.

"Many parents will be alarmed at the threat of preventing them knowing how their children are doing at school.

"It would be an absolute betrayal for teachers to boycott these tests. I hope that teachers throughout the country will vote against strike action if they are given the choice."