Peter Smith, general secretary of the Association of Teachers and Lecturers, said teachers should be paid in line with the nurses' award of 4.7 per cent.
He also said it was unfair that heads will get a rise of between 6.5 per cent and 9.5 per cent - substantially more than classroom teachers.
But headteachers' leaders say the figures quoted in the Government's pay award to their members is misleading.
Unions were responding to this year's pay review body report, which set out the salary proposals.
David Hart, general secretary of the National Association of Head Teachers, said many heads will be getting far less than the quoted figures.
He asked why the Government had tried to mislead the profession, at a time when it is considering the Green Paper and its emphasis on performance-related pay: "Any performance-related pay system critically depends for its success on mutual trust and confidence. The spin put on the award has contributed to the undermining of that trust."
The NAHT said it rejected the notion that the rise would adequately reward heads for their new responsibilities in implementing performance management systems.
The association also questions the new school groupings, based on pupil numbers weighted by key stage. Heads' pay will be determined by performance within a pay range within each group.
The Secondary Heads Association supports the increase in groups, but believes there should be more. John Dunford, general secretary, also told Ms Morris the 3.5 per award for teachers was not enough to recruit or retain.