Students may attempt to gain an “unfair advantage” by submitting work which is not their own to enhance teacher judgments, exam boards have warned.

Schools have been told to make sure that private tutors have not given “inappropriate levels of support” to students when completing work which could be used as evidence for deciding grades this summer.

Incidents where students have submitted “fabricated” or plagarised work to improve results will be treated as malpractice, according to the guidance from exam boards on how to determine grades.

Teachers in England will decide GCSE and A-level grades after this summer’s exams were cancelled.

Earlier this week, Ofqual warned that exam boards could intervene over allegations of parents or students who have placed inappropriate pressure on teachers to submit higher grades.

The latest guidance from the Joint Council for Qualifications (JCQ) says exams boards should be informed of students who continue to “inappropriately attempt to pressure” teachers over grade decisions.

Any “credible allegations” will be dealt with under the JCQ’s suspected malpractice policies and procedures – which could lead to sanctions against students, such as loss of marks or disqualification.

The guidance warns: “It is possible that some students may attempt to influence their teachers’ judgments about their grades. Students might attempt to gain an unfair advantage during the centre’s process by, for example, submitting fabricated evidence or plagiarised work.”

This year, teachers will be able to draw on a range of evidence when determining pupils’ grades, including mock exams, coursework, and assessments using questions provided by exam boards.

These additional materials can be set as a test, including remotely if required, or as a class or homework activity, the guidance from exam boards says.

But it warns: “If this work is going to contribute towards the determination of a student’s grade, it must represent their own work.”

Exam boards say that robust mechanisms should be in place to ensure that “teachers are confident that work used as evidence is the students’ own and that no inappropriate levels of support have been given to students to complete it, either within the centre or with external tutors.”

“Awarding organisations will be investigating instances where it appears evidence is not authentic,” the guidance adds.

Headteachers are concerned that schools and colleges only have 12 weeks before they must submit grades to exam boards, adding that the wait for detailed guidance on awarding grades was “frustrating”.

On possible attempts to influence grades through pressure, Geoff Barton, general secretary of the Association of School and College Leaders (ASCL), said: “The vast majority of parents and students are very supportive of their schools and colleges, and would not dream of behaving in this way.

“But we need the small minority who may be inclined to over-assert their viewpoint to respect the fact that teachers and centres will be making professional evidence-based judgements in a way which is designed to ensure all students are treated fairly and equally.”

He added: “It is frustrating that schools and colleges have had to wait for detailed guidance on awarding grades for nearly three months since the Education Secretary cancelled exams and promised that contingency arrangements just needed some fine-tuning.”

Paul Whiteman, general secretary of school leaders’ union NAHT, said: “We remain disappointed that schools have had to wait three months for the details of these plans.

“It would have been far better for the government to discuss and consult on a “plan B” much earlier to avoid unnecessary confusion and worry for students.”

Philip Wright, director general at JCQ, said: “JCQ and the awarding organisations appreciate the urgent need for detailed guidance on how grades will be awarded fairly and appropriately this summer.

“We have worked with Ofqual and the DfE to ensure our guidance has been published as quickly as possible following the outcomes of the conclusions of their consultation.”

Education Secretary, Gavin Williamson, said: “The guidance published today will support teachers with those decisions and support schools and colleges with their own processes, helping to maximise consistency across the country and ultimately maximise fairness for our young people.

“We trust teachers in their decision-making and students can be confident that they will receive grades that enable them to progress to the next stage of their lives.”