The scottish Secondary Teachers' Association has relaunched its attack on the Government's new exams to replace Standard grades and Intermediates.
Ann Ballinger, SSTA general secretary, claims the plans to introduce what she describes as a "two-tier" assessment system - with one set of exams assessed externally and the other internally - is being driven by financial considerations.
"Under the proposals, pupils who will sit the examinations intended to replace the current (Standard grade) Credit examinations, will have at least one examination paper which is externally marked. Pupils sitting General and Foundation replacement examinations will sit papers marked only within the school," she said.
Exams marked in the school would never lead to qualifications with the same degree of acceptance as those marked externally, she said.
"These proposals are made solely on the basis of minimum cost, with no consideration given to their impact on young people," she added.
There was also insufficient funding to support the writing of new courses for Curriculum for Excellence, provide continuing professional development or pay for supply cover for teachers doing development work, Mrs Ballinger commented.
"It is unacceptable to damage the prospects of the current Primary 7 pupils by introducing them to a secondary curriculum which is, at best, only partially developed," she added.
A spokesman for the Scottish Government said: "Assessment proposals for the new national qualifications have not yet been finalised and the Education Secretary will not sign these off unless he is satisfied they are workable and will improve national standards for the benefit of Scotland's young people."
The Scottish Government had agreed not to have an external exam for the new National 4 qualification on the basis of "the unanimous advice of the teachers and educational experts who oversee the new curriculum".
He added: "There has been unparalleled involvement of the education profession in the development of Curriculum for Excellence and all the teacher bodies, including the SSTA, have been fully involved in this process."