A GCSE paper has been withdrawn after examiners shared "inappropriate" information.
The information and communications technology paper, due to be taken in January, was set by the Welsh exam board (WJEC). The company has been embroiled in the cheating allegations recently exposed by The Telegraph, who covertly filmed exam officials giving "advice" to paying teachers.
The decision to withdraw the paper was made by Ofqual after an urgent report ordered by ministers earlier this month said the paper had been compromised. The report found the move was necessary to protect the "integrity and security" of the qualification.
"This is in clear breach of regulatory requirements, and it compromises the planned exam," the report said.
Exam chiefs were grilled by MPs last Thursday to establish whether allegations made by The Telegraph were true. The broadsheet accused WJEC and Edexcel exam officials of giving unfair advice on how to boost exam results and making tests easier in order to attract more business.
During the House of Commons education select committee questions, Paul Barnes and Paul Evans, both from WJEC, along with Steph Warren from Edexcel, adamantly insisted they had been "misrepresented". Barnes even went so far as to claim the footage had been edited by The Telegraph before being published.
Warren, who was filmed allegedly saying: "there's so little content we don't know how we got it through," vehemently denied the allegations.
"My daughter has transcribed the footage and I did not say that. It is not true," she told the committee.
The scandal, which allegedly saw teachers paying up to £230 for seminars, has already prompted calls for the exam board system to be reformed. On 10 December, Michael Gove announced he would consider the move but would wait for Ofqual's investigations into the allegations to be completed.
Glenys Stacey, Ofqual chief executive, said she welcomed the work The Telegraph had done to "bring these concerns to light".
"The information provided is a valuable contribution to our wider programme of work, already underway, into possible conflicts of interests among exam boards.
"This update outlines our initial plans and findings and the actions taken to protect future exams. Where we have found evidence that a question paper has been compromised we have taken action.
"We are continuing our work to study the material provided. There is no evidence at this stage that other exams in January are similarly affected."
The ICT paper will be amended and the 450 pupils due to sit the exam in January will now take it in March. The move will not impact on when students will be able to complete their GCSE course in the subject.
WJEC said 11 schools and colleges in England and Wales were being contacted regarding postponing the exam.
"The decision was made after it became apparent that advice given to teachers at recent professional development events had not been available to teachers at all 11 centres with candidates for this examination," a spokesman said.
"The advice related to the scope of one of the possible areas to be covered in the exam, representing less than 2% of the qualification's marks."
"Once we discovered that information had been given to some, but not all teachers about the scope of areas to be covered in the January exam, we advised Ofqual and DfES immediately," Gareth Pierce, WJEC's chief executive said.
"As always, the interests of candidates are uppermost in our minds."
Ofqual's investigations were originally launched in response to the errors that occurred in GCSE and A-level exam papers during the summer. The exam watchdog said there was a "number of risk factors" around the current procedures.
"These include insufficient focus on quality early in the question paper process, leading to changes being made late on and a lack of clarity around the roles, responsibilities and accountability for those involved in the process."
Shadow education secretary Stephen Twigg called for "structural change" to exams to ensure a correct balance between competition and standards.
The report demanded each exam board to make changes to address "specific weaknesses" and undertake shorter-term checking measures to protect future exams.
BBC education correspondent Gillian Hargreaves said the blunders and allegations had caused a "crisis of confidence" in the exam system.