Thousands of students face further delays to finding out if their A-levels are going to be re-graded.

Details of how the re-grading would be applied had been set to be announced on Tuesday - but this will now not known until Wednesday.

The head of the independent inquiry, Mike Tomlinson, said exam boards wanted time to "double check" their work.

"It's important that we get this right," said Mr Tomlinson.

Tomlinson - new A-level system was 'accident waiting to happen'

But Mr Tomlinson's inquiry will not necessarily specify which subjects or individual course units will be re-graded - or how many students could be affected.

The independent inquiry will lay out the "methodology" for re-grading, but it will be up to individual exam boards to put this into practice.

This could mean further confusion for students who have already opted to take second or third choice university places on the basis of their existing grades.

'Clear-up'

The announcement on re-grading will begin the next phase of the clear-up operation after the disputed A-level results.

The three exam boards - OCR, AQA and Edexcel - will have to work out which subjects and papers have to be re-graded, which will see thousands of candidates receiving higher grades.

In his report on the way exam boards - especially the OCR board - manipulated this summer's A-levels, Mr Tomlinson said chief executives had overruled the grades recommended by their chief examiners.

Estelle Morris still faces a complicated clear-up after the exam fiasco

The chairman of the QCA exams watchdog, Sir William Stubbs, was sacked on Friday by the Education Secretary, Estelle Morris even though the report by Mike Tomlinson had cleared him of any wrongdoing.

She said he had to go because he had lost the trust of the exam boards and schools.

Mr Tomlinson - the former chief schools inspector in England - attached no direct blame to anyone in his report.

He said the new A-level system was "an accident waiting to happen".

But because the code of guidance on the maintenance of standards was vague, the exam boards were not operating outside it.

Wider complaints

The sacking of Sir William Stubbs - who is complaining he was dismissed unfairly - temporarily drew attention away from the questions left unanswered by the Tomlinson report.

But there are signs that it has not satisfied everyone.

For instance, Mr Tomlinson specifically did not look at the marking of papers - only the subsequent assignment of grades to those marks.

Many students believe they have been marked unfairly.

The issue of otherwise A-grade students failing one of their exam modules was simply not mentioned.

The word "coursework" - believed by many to have been a particular target of downgrading - is not in the report.

Also, there has been a steady string of "what about us?" complaints about this summer's AS-levels, whereas the Tomlinson Inquiry looked only at the second stage of the new A-levels, the so-called A2s.

AS results

But Mr Tomlinson also has his suspicions about this summer's AS-levels.

He has asked the exam boards to include data on those in his effort to establish the extent of the re-grading that needs to be done this week.

On the face of it there are reasons for doubt.

In OCR's English Literature AS-level coursework unit, for example, the proportion who got an A grade last year was more than 36%.

In that unit this year - when teachers had had more experience of the course - the A grades were just under 30%.

The overall pass rate fell from 98% to 94%.

Mr Tomlinson is to go on to consider the wider issue of whether the standard of the A-level has been maintained, with a further report due in November.

But there are also calls for a more far-reaching investigation, taking in GCSEs and even national curriculum tests.

The Conservatives' spokesman, Damian Green, has called for the QCA to be replaced by a "truly independent" exams regulator.