The National Union of Teachers has given the go-ahead for a ballot on a boycott of next spring's national tests for seven and 11-year-olds in England.

Charles Clarke, education secretary, said: "A boycott of tests would be a gross betrayal of children. It would say that we don't care how children are doing or how we can better help them in school.

"We would urge any member of the NUT to vote for children and against industrial action.

"National testing has a very clear moral purpose. It means we have high expectations for every single child.

"It enables schools to tailor their teaching to each child's needs. And we can compare each child's progress with that of other children.

"We are absolutely committed to ensuring pupils experience a rich and full curriculum and are motivated to learn - but not at the expense of getting the basics right.

"The best schools do both. For children from poorer backgrounds, national testing is particularly important to raise basic standards.

"Too many used to be written off as if they were somehow predestined to fail. Testing ensures that they get the support they need.

"Abandoning testing would not 'free' pupils to learn. Moreover there is no question of going back to the bad old days when they were let down so badly. We have no intention of removing this vital source of information from parents and the wider community.

"We have listened to sensible concerns about testing at seven and are reforming the way in which the tests are conducted to give teacher assessment a bigger role and we are always ready to discuss improvements in the system. But national tests at seven, 11 and 14 are rightly here to stay".

Phil Willis, education spokesman, said: "If there is evidence that testing improves performance we have yet to see it - weighing children does not making them heavier.

"The results point in exactly the opposite direction: Performance has stalled, the curriculum has narrowed, children are more stressed and teachers' professional judgement is being undermined.

"There is widespread concern amongst parents, teachers, educators and MPs over the current regime of tests which makes our children the most tested in the world.

"Charles Clarke would be well advised to seek a meeting with the National Union of Teachers to discuss their concerns rather than continue his vendetta against their members."

Forum Response: National Union of Teachers

Doug McAvoy, NUT general secretary, said: "The NUT has sought a meeting with the government to press for a review of testing in England. It has ignored that request.

"Teachers in England do not understand why they and their pupils should be treated differently from those in Scotland and Wales.

In Scotland following a review, national tests are to be replaced by teacher assessment. In Wales Key Stage 1 tests have been abandoned and a review of Key Stage 2 and 3 tests is underway.

"The stubbornness of the government in refusing to discuss with us a similar review for England will add to the anger of teachers.

"It is only the government that fails to recognise the inadequacy of these tests and the damage they cause to children's education not least because of the constraining affect they have on teachers' professional judgement.

"Across the country teachers and parents are tired of the disruption these tests cause to their children's education.

"When the boycott goes ahead, no child's education will be disrupted.

"Instead teachers will be able to use their professional judgement to their pupils' benefit and in support of their primary purpose of educating children.

"At Key Stage 3, the government now plans to introduce a new set of league tables based on test results.

"In the light of this change, the union will do further work with members in secondary schools prior to a ballot to boycott Key Stage 3 tests.

"In recognition of the review in Wales, the ballot will be confined to members in England. When we know the results of that review, the position of teachers in Wales will be looked at again."