Nigel de Gruchy, general secretary of the National Association of Schoolmasters/ Union of Women Teachers, launched his attack after Christine Blower, of the National Union of Teachers, admitted letting her 11-year-old daughter stay at home for three days last year to stop her sitting the compulsory tests in English, maths and science.
Addressing the NUT conference in Harrogate, North Yorkshire, at the weekend, Ms Blower told delegates that they, too, should take direct action to oppose national testing, school inspection and large classes.
The NUT strongly opposed the introduction of the tests for seven-, 11- and 14-year-olds. Mr De Gruchy, speaking before the opening of the NASUWT's annual conference in Bourne-mouth, Dorset, accused Ms Blower of disgracing the profession "by organising her own child to truant". He said: "You can't have your cake and eat it. You can't argue for a state education system and then in effect argue that every parent has the right to do whatever they like."
The move set a "very dangerous precedent" he added. "If every time parents disagreed, they retained the right to withdraw their child, there would be chaos."
Ms Blower, 45, of Hammersmith, west London, who teaches children with behavioural difficulties, pledged to remove her second daughter, Eleanor, 6, from school during the key stage-one tests in maths and English which she is due to take next year. She told the conference: "As a parent and teacher I will continue to support campaigns to rid education of blanket testing on our children."
The clash exposes divisions between the main teaching unions which appear to be widening in the run-up to the election. While NUT delegates voted to ballot for strike action if a new government failed to cut class sizes to a maximum of 30, Mr De Gruchy went out of his way to stress that the NASUWT conference would "certainly not be threatening an in-coming government ... with strike action in the next month or two if problems which have built up over the last couple of decades are not immediately resolved".
However, he spoke of his "alarm" at leaked Tory manifesto proposals to ban strikes by teaching unions, describing the move as "naked fascism". He said: "If that is what the Conservative Party is proposing then it is high time for the nation to wake up. It might be teacher trade unions today. Tomorrow it could be the press."