Pupils at St John’s in Marlborough are worried they may have to resit an AS-level coursework module after allegations a teacher helped students pass the assessment.

The claims are now being investigated by the exam board and the Gazette understands a senior member of staff overheard that students did not follow exam conditions in a test.

It is believed that the accused teacher – Dr Christopher Chadwick – asked pupils to come back during half-term to change their answers.

Dr Chadwick, team leader for chemistry, is alleged to have talked students through the questions in an assessment that is supposed to be held in silence.

An internal investigation at the school has been completed and its findings passed on to the exam board, AQA, which will decide how to proceed.

Letters have been sent to the parents of pupils affected, telling them about the investigation.

One parent said: “It’s very worrying because we don’t know what it means for the other chemistry pupils who aren’t in his class.

“I don’t know if the pupils in his class have been told what will happen if it’s proven that there has been cheating, but my son is studying chemistry and we haven’t heard anything from the school to say he won’t have to resit his exams.

“We’re just in limbo and kids are under enough pressure with exams without adding to it.”

According to the school, Dr Chadwick is not teaching there, but has not been suspended.

Chemistry staffing has been reorganised so all classes are taught by a qualified chemist, to minimise disruption to students.

Principal Patrick Hazlewood said: “We’ve completed our investigation and the exam board are investigating it at the moment. Once they have completed this, they will let us know whether they have decided to take any action and then we will respond appropriately.

“I have requested that the results of the inquiry do not affect the pupils, because this was a situation that was out of their control.”

The school has been told that the malpractice committee is likely to discuss the allegation in a couple of weeks’ time.

During the investigation, students were questioned by senior members of staff and asked to make statements.

Exam board AQA said that investigations regarding malpractice were confidential, so it was unable to confirm whether or not a specific investigation was currently taking place.

A spokesman said: “We take all allegations of malpractice extremely seriously and ensure that appropriate action is taken to safeguard the interests of students and protect the integrity of our examinations.”