A TOP state school in one of the most affluent areas in Scotland is being investigated after concerns it may have breached exam rules.

Officials launched an inquiry into Mearns Castle High School, in East Renfrewshire - one of the country's best-performing secondaries - after being made aware of potential malpractice.

The Newton Mearns school, which has denied any wrongdoing, issued letters to parents in February updating them on procedures surrounding Higher assignments in geography, history and modern studies.

Assignments, which are worth around one third of the overall marks, take the form of an essay based on pupil research.

The write-up for the assignment takes place under exam conditions, but pupils are allowed to submit drafts of their work in advance so teachers can give them "reasonable assistance" to ensure they are on the right track.

However, assignment guidelines from the Scottish Qualifications Authority (SQA), state explicitly that "at any stage" reasonable assistance does not include "providing detailed feedback on drafts including marking".

The letter from Mearns Castle's principal teacher of social subjects states: "All pupils are required to hand in draft sections of their write-up on allocated dates to be marked and given feedback on.

"It is each pupil’s responsibility to meet these deadlines, make the appropriate changes to their work based on feedback received from their teacher and seek additional support if necessary."

An SQA spokesman said officials had been been made aware of a potential issue relating to conditions of assessment for Higher assignment work.

He said: "SQA’s criteria on assessment conditions and the assistance which teachers and lecturers can give to candidates are clearly published on our website and in course materials.

"As in all cases where potentially serious matters are raised with SQA we will now investigate what has happened.

"SQA takes very seriously its obligation to ensure fairness and equity for all candidates in all qualifications through consistent application of assessment conditions."

An East Renfrewshire Council spokesman said staff were well aware of the SQA guidelines in relation to Higher assignments and these were followed "rigorously" across the authority.

He added: "At no stage was any pupils’ Higher assignment marked. This letter, which unfortunately was poorly worded, was simply issued to stress the importance of these assignments to parents.

"Staff provided support and advice to pupils in preparation for completing their assignments under exam conditions, as is permitted by the SQA, which is what this letter is referring to.

"It is important to stress that the wording of this letter does not accurately reflect the role staff at this school play in supporting pupils with their Higher assignments, and this has already been amended for the forthcoming session."

SQA guidance states that malpractice can arise for a variety of reasons including "intentional" incidents aimed at giving an unfair advantage.

The exam body also highlights the fact that some incidents arise due to ignorance, carelessness or neglect in applying the requirements - which it terms maladministration.

The guidance states: "Whether intentional or not, it is necessary to investigate and act upon any suspected instances of malpractice, to protect the integrity of the qualification and to identify any wider lessons to be learned."

It is understood the SQA has no plans to remark essays if malpractice is uncovered given the impact on pupils who have now received their exam results and are progressing on to higher education or other career options.

Mearns Castle is one of the best-performing schools in Scotland in terms of exam success and regularly features in The Herald's league table of the top state schools.