Nearly 1,300 school governing bodies plan to boycott primary league tables, the National Association of Head Teachers reported this week.
Schools have to send results of national tests for 11-year-olds to marking agencies by July 31 if they are to be included in next year's league tables An NAHT survey of 12,000 of the country's 25,000 primary schools has so far produced 3,436 returns. A total of 1,272 (42 per cent) governing bodies will boycott the tables; 1,740 will report the results to the agencies; and 424 have yet to decide.
The union claims the boycott will mean that teacher assessment cannot be included in the official figures and that externally-marked tests will not be checked by the schools which take part.
But Gillian Shephard, the Education and Employment Secretary, said governors who took part in the boycott would be breaking the law. And she added: "We have the test results and we will publish them. It is bizarre that the very information teachers themselves pressed us to put in the tables - their own assessments of pupils - is the information they want to suppress.
"Schools that do not provide this information will be identified in the tables. Those who would wish to deny parents and the wider public important information on how children are progressing are living in the past. Parents will be amazed by their actions. Performance tables for schools are here to stay."
David Hart, the NAHT's general secretary, said: "The Secretary of State's rhetoric to the effect that millions of parents are dying to get their hands on the league tables next March is way over the top. She would have achieved a great deal more in her relationship with governors and parents if she had waited for the tests to bed down."
The association criticised the Government's U-turn in February when Mrs Shephard announced there would be primary league tables, only 10 days after she had said the opposite because the tests were not "fully bedded down".
Mr Hart said the association was still receiving complaints from schools about the test questions and "bad marking".
Many schools not taking part in the boycott would be reporting the results reluctantly, he said, and would be writing letters of protest to Mrs Shephard.
But he stressed that the boycott only applied to 1997 and that the NAHT had made no decision about league tables in 1998 onwards.
The Nation Confederation of Parent-Teacher Associations also gave the key stage 2 league tables the thumbs down this week. A survey of its member schools showed that 95 per cent of returns said "no" to league tables next year.
But the boycott has been denounced by the National Association of Governors and Managers, who said governors should not be breaking the law.
Pat Petch, chair of the National Governors' Council, said this week that: "The NAHT claims that some primary schools will not be sending in teacher assessment results. The NAHT may think that a victory but they have failed to consider the effect of such action on the schools themselves.
"It is difficult to see how anything other than damage can be done by withholding teacher assessment. Governors, with broader responsibilities and greater objectivity, are more concerned to set the record straight."