Michael Gove has said students were let down by a "not entirely fair" exam system but attributed the blame to his predecessors.
The education secretary made the comments prior to his appearance in the House of Commons on Monday afternoon. He is facing calls to come to Parliament and make a statement on resolving a growing row over the grading of GCSE English exams.
Speaker John Bercow may face a request for an Urgent Question to the education secretary if he does not ask to make a formal statement.
Labour's education spokesman Stephen Twigg yesterday urged Gove to answer questions on the row, which began after it emerged GCSE English grading boundaries had been altered between January and May exams, meaning some students predicted to obtain a C grade finished with a D.
Trade unions have threatened legal action over the issue but exams regulator Ofqual has said it would be inappropriate for either of the sets of exams to be reconsidered. Resits will be allowed earlier than normal in November.
Twigg said Gove had to lead on the issue when speaking on yesterday's Sky News Murnaghan programme.
He said: "Parliament comes back tomorrow and we expect him to come to Parliament and to set out what's going to happen because there is a basic unfairness here. If you were assessed in January you could get a grade C. The same quality of work, maybe even slightly better work, assessed in May and you would have got a D. That cannot be right.
"I'm all in favour of rigour, I'm in favour of making sure these are tough exams, but you can't change the boundaries in the middle of the year.
"We need a full inquiry into what went wrong, we need to make sure this doesn't happen again next year, which is why I have suggested the select committee on education should take a detailed look at that.
"But before then, we need to try and avert there being legal action... let's try to resolve this in the next few days.
"I think the secretary of state, Michael Gove, should be calling Ofqual and the exam boards in to try to sort this out so that these young people aren't at a disadvantage."
Writing in the Mail on Sunday, prime minister David Cameron defended the need for tougher exams.
He said: "In schools there will be no more excuses for failure; no more soft exams and soft discipline.
"We saw that change in the exam results this year. When the grades went down a predictable cry went up: that we were hurting the prospects of these children.
"To that we must be very clear: what hurts them is dumbing down their education so that their potential is never reached and no one wants to employ them. 'All must have prizes' is not just patronising, it is cruel - and with us it is over."
Speaking on BBC Breakfast, Gove denied putting pressure on exam boards to make grading tougher.
He said: "No, I absolutely did not put any pressure on any exam boards.
"I made it clear that no pressure was put by central government, by me or any other minister, on any exam board.
"How each exam paper is marked and how the marks are allocated is ultimately a decision for the exam boards.
"I cannot interfere in that process."
Responding to calls by angry students to answer questions over the row, the education secretary said he had "an enormous amount of sympathy" for those who had not received the grades they were expecting.
But he said the government was not to blame, insisting students had been let down by an "inherited" exam system that is "not fit for purpose."
"I feel that they were let down," he added. "The exam was designed in a way that I don't think was entirely fair for them."
He said the current system of splitting subjects into modules and allowing students to sit the exams at different times was to blame for grade inflation.
"I think the GCSEs shouldn't be modular examinations," he said.
"We have made changes to make sure they won't be split up in that way.
"All the exams will be taken at the same time in the same way.
"The situation we inherited that was designed before we came to power was not fair."
Vowing to reform the system, he added: "What is right is that we make sure that in the future we make sure this situation cannot occur again by making sure our exam system is reformed."
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