The examination board at the centre of controversy over a series of blunders is accused of "failing to meet its responsibilities" to schools in a report published today.
Edexcel has been given a reprieve from losing its contract in September as had been threatened by ministers, but has been told by the Qualifications and Curriculum Authority that it has four weeks to show how it will improve for this summer's exam season. It will face a further review of its performance in the autumn.
The QCA, the Government's exams watchdog, accused Edexcel of providing "poor service" to many customers in 2001 after hundreds of exam results arrived late."Most of this has been the result of shortcomings in processing examination results and Edexcel's poor handling of its post-results service," it added.
The exam board had underestimated the number of youngsters entering for AS levels "and therefore underestimated the number of examiners required". As a result a "significant" number of scripts had not been allocated to examiners.
The report also voiced concerns over the production of exam papers, warning that graphics and icons were sometimes omitted from the draft papers leading to "errors" and "inappropriate" graphs in the final papers.
The investigation was set up after it was revealed last week that a printing error in an AS level maths exam had rendered a question unanswerable and a page in a communications exams paper had been omitted in error.
Estelle Morris, the Secretary of State for Education and Skills, was said to be "absolutely furious" over the errors and aides said the exam board could be stripped of its licence to supply GCSE, AS and A level papers when its contract came up for renewal in September.
Ms Morris said today's report highlighted "a number of unacceptable shortcomings in Edexcel's quality assurance, handling of exam results and its service to schools."
She said she expected "more rigorous checking during every stage of the production of exam papers". John Kerr, chief executive of Edexcel, said: "My colleagues and I are deeply sorry about the errors."