BRITAIN'S biggest headteachers' union today raised the prospect of a ballot for industrial action as part of a major campaign against school tests and league tables.

Mick Brookes, general secretary of the National Association of Head Teachers, said the tests were "ruining" the education of 11-year-olds while league tables "demoralised" schools.

Parents could even be invited to send their children to school late so they miss the tests completely, he added.

"If fewer than two-thirds of pupils turn up, that would invalidate the result," he said. There would then be no data to include in league tables.

But the Government refused to back down, insisting that league tables and the national curriculum tests on which they are based were "non-negotiable".