England's exams watchdog has announced a review of rules allowing teachers to set question papers in the wake of allegations of exam leaks.

Teacher involvement in writing and reviewing exams has "many benefits" and malpractice is rare, but access to live exam materials, such as papers due to be taken by students, needs to be "appropriately controlled" and risks to security kept to a minimum, Ofqual said.

It said it will conduct a review of current rules and safeguards in place to stop confidential information being disclosed.

The move comes after two high-profile private schools became embroiled in a controversy over exam breaches.

Last week it emerged a senior staff member at Eton College had left the prestigious boys' school amid allegations he shared confidential information in relation to an upcoming Pre-U economics exam with other teachers.

Eton parted company with Mo Tanweer, head of economics and deputy headmaster of academics at the public school, after an investigation by the Cambridge International Examinations (CIE) exam board, it was reported.

The CIE has also been investigating concerns about irregularities surrounding Pre-U art history at both Eton and Winchester College.

Pre-U qualifications are an equivalent standard to A-levels.

In a statement, Ofqual said: "Ofqual will conduct a review of the rules under which serving teachers take part in writing and reviewing question papers, and the safeguards in place to prevent disclosure of confidential information.

"The involvement of serving teachers in the process of exam setting has many benefits and exam malpractice by teachers is rare.

"However, access to live materials must be appropriately controlled and risks to security minimised. We will investigate whether the safeguards in place are sufficiently robust and whether changes are needed."

A progress report will be published later in the year, the regulator said.

Geoff Barton, general secretary of the Association of School and College Leaders (ASCL), said: "We are talking about a profession that has always had an under-pinning sense of trust."

While there have been a small number of "bad examples", action has been taken swiftly, Mr Barton said, adding that it is important that teachers are involved in the exam process.

In its latest statement regarding Pre-U economics, Eton said that a CIE investigation concluded that "maladministration had occurred in relation to one paper as a result of the actions of one of Eton's teachers, in that a revision exercise that he had circulated to other teachers at Eton contained confidential information which breached exam security.

"Eton was appalled that one of its teachers, who was also a principal examiner for CIE, had acted in this way," it added.

The school said that the teacher had been dismissed, no other staff member was implicated in any wrongdoing and that pupils had been "inadvertent recipients" of confidential information.

In the case of Pre-U art history, Eton said: "Following an investigation by CIE, the exam board judged that pupils at Eton who sat Pre-U art history this summer were inadvertent recipients of confidential information about one paper.

"This related to practice questions set by a teacher from another school and sent on by a pupil at that school before the exam. No member of staff at Eton was involved in any way."

Winchester College said it had treated the matter "with the utmost seriousness" and "greatly regrets what has happened".

"No boy was to blame for the exam irregularity, and the Board used standard procedures to award final grades," Winchester said.

"One teacher has retired from the school, and all those boys holding university offers dependent on a grade in art history have now had those offers confirmed by their first or second choice university."

It is understood that teachers can be involved in the process of setting exam papers for the qualifications that they teach.