Chief regulator Glenys Stacey says Ofqal has noticed a pattern in appeals of exam results from schools.
Schools are playing the exams system by appealing against results in a bid to improve pupils' grades, the qualifications regulator has said.
Ofqual suggested the current GCSE and A-level appeals process was designed for a "more innocent era" and is being tactically used by teachers under pressure to secure good results.
In a new report it said that evidence suggests an increase in appeals against results, particularly those that are within one or two marks of key grade boundaries - such as C/D at GCSE and A/B at A-level.
It also found that examiners dealing with appeals may be looking for extra marks to award to students as they are conscious that the final result could have a major impact on a youngster's future.