Sources close to the Qualifications and Curriculum Authority said the regulator has not properly investigated why grades have been consistently improving.
The Government is to split the organisation to include an independent regulator reporting to Parliament. Educationists hope this will lead to a more robust analysis of exam trends.
Although there was no direct pressure from ministers for exam scores to rise, a source said: "There's a general culture at QCA that things (results statistics) cannot go down. They have to go up and they have to go up by a few percentage points every year.
"It just hangs there in the corridors. Talk to anyone and they will tell you about it.
"There is a general expectation at QCA and at the Department for Education and Skills and its successor of slowly rising attainment. All downward movement is questioned as to whether it's valid.
"All upward movement is cited as evidence of rising standards - although too much and then it's questioned as slipping standards. This culture has sanctioned slow upward movement (in the statistics)."
The source added that exam boards did not seek to lower standards. But the effect of changes to the structure of GCSEs and A-levels, including making them more modular and repeated revisions to syllabuses, was not properly monitored by the QCA.
A second source said that the test and exam system was now so complex that definitive answers on whether standards were rising or falling were fiendishly difficult.
A senior exam board figure said the authority no longer regulated standards in any detail - most of its time was spent on other work, including revisions to the curriculum and on the introduction of new exams.
A QCA spokesman said the authority did consider the issue of standards over time and that reports on at least one GCSE and A-level subject had pointed to a change in the standard of particular exams.
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