The Education ministry and Knec have been accused of colluding to deliberately fail candidates who sat for the 2016 KCSE exams.
Knut secretary general Wilson Sossion on Thursday said last year's exam results were "cooked" and hurriedly released "with a view to condemn teachers as non-performing".
Out of 500,000 candidates who sat the exams, only 141 straight As were posted.
Education CS Fred Matiang'i also said only 88,929 students scored between A and C+ (plus), therefore gaining guaranteed slots in public universities.
Sossion alleged that the Kenya National Examinations Council omitted crucial stages while processing exams.
"It should be noted that the examiners were not allowed to consult on the wide range of marks before awarding them to students and in some cases, a predetermined highest mark to be given was set," he said.
Sossion made his remarks before the National Assembly Education Committee.
He was accompanied by senior Knut and Kuppet officials. Sossion said his presented was harmonised version of both Knut and Kuppet's grievances.
The marking scheme, he said, was made deliberate for the students to fail with strong bias against the boys who posted poor scores in humanities.
"Even in cases where the question has been repeated from previous KCSE past papers, the marking differed sharply," Sossion told the committee.
The Knut boss attributed the "huge and unprecedented disparity" in the number of boys and girls who passed to using one grading system for all subjects.
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"Everything was hurried, no cross-checking was done, no verification or validation was done. There was poor coordination of marking," he said.
"Teachers’ unions were not part of the release of the results, a very unfortunate departure showing an unprecedented curse," Sossion told the MPs.
He said the criterion referencing allegedly used by Knec in marking the 2016 papers was unacceptable, given that word-over examinations are tested using normative marking system.
This system, he said was the reason why more girls who largely take humanities and two science subjects, had more A grades than boys.
"Unless moderation is done we will never be associated with the results of 2016. The education sector has a dangerous cancer and it is on fire," Sossion said.
He said the results should be recalled for moderation - an act he said will not disadvantage anyone including those who scored A grade.
"It is not too late, Parliament should assert its authority on this matter to redeem the education sector facing a dangerous policy shift," he added.