In a letter to John Patten, Secretary of State for Education, the unions said suspension of the tests would also 'release teachers from the excessive workload resulting from the current system of assessment and testing'.
The unions rejected suggestions that the looming general boycott of tests would disrupt children's education. They said it would free more time for teaching: 'Parents will continue to receive full information about their children's progress.'
However, they welcomed Mr Patten's decision to review the national curriculum, and the commitment made by Sir Ron Dearing, the new chairman of the curriculum and testing authorities, to include the unions in his consultation.
But Mr Patten made it plain that he had no intention of suspending this year's tests. Instead, he launched a pounds 700,000 campaign in their defence. In a leaflet, How Is Your Child Doing at School?, Mr Patten argues that it 'would be a tragedy for everyone if this summer's tests did not go ahead as planned' - a view which he says is shared by many teachers and governors. The leaflet quotes several anonymous teachers defending the tests.
'Our children are our investment for the future. We must make sure they have every chance to realise their true potential. Tests are the means by which we can give them that chance,' Mr Patten said. Tests were essential to give information about children's strengths and weaknesses and help plan for the next stage of schooling.
As yet, only one union is boycotting preparations for this summer's tests - the National Association of Schoolmasters/Union of Women Teachers, which mostly has members in secondary schools. The Association of Teachers and Lecturers will release the results of its ballot on Friday, and the National Union of Teachers is expecting to complete its ballot on 10 May. If both support the boycott, virtually every state school in England and Wales will be affected.
Doug McAvoy, general secretary of the NUT, yesterday wrote to headteachers and governing bodies urging them not to try to force teachers into carrying out the tests. Last week, Mr Patten wrote to heads and governors pointing out that they have a statutory duty to deliver the tests. Mr McAvoy says that heads and governors 'can only be expected to take reasonable steps to fulfil that duty'.