Exam markers were accused of making school students the victims of political football today, after results showed the first decline in results in GCSE history.
In all subjects, the number of students achieving the A* grade was down 0.5%, while the number earning marks between A*-C was down 0.4%.
Critics say the reduction is the result of new rules designed to stop 'grade inflation', where the number of A grades goes up year after year. That phenomenon convinced education secretary Michael Gove the system was becoming discredited.
"There is unacceptable confusion today about whether so-called grade inflation has been banned and grade boundaries made tougher," said Adrian Prandle, education policy adviser at the Association of teachers and Lecturers.
"Children's chances in life are at stake here and it is hugely unfair to make today's 16-year-olds the victims of political football. It is wrong to make improvement impossible."
The number of English students scoring A*-C fell from 65.4% to 63.9% while English Literature fell from 78.4% last year to 76.3%.
The decline in results will be a significant disappointment to many pupils, who may be unable to attain places in sixth form.
It will also damage schools, which face being converted into academies if their results fall below a certain level. Some critics suggest the downgrading of results allows Gove to push ahead with the expansion of the controversial academies programme.
"We need to understand why results have fallen in [English and maths]. Is it because of pressure from Ofqual to shift grade boundaries?" shadow education secretary Stephen Twigg said.
"Concerns have been raised regarding the English GCSE in some quarters. As well as ensuring standards remain rigorous, we must ensure all pupils are treated consistently and fairly."
Speaking on the Today programme, the head of exams regulator Ofqual denied markers had been particularly harsh this year.
"It's just the case that because qualifications last over two years, they're taught over two years, it takes a little while for these changes to work through the system," Glenys Stacey said.
"So, I'd like to make that clear, we are continuing to apply a measured approach to the control of standards."
Around 658,000 16-year-olds in England, Wales and Northern Ireland receive their results today.