A Conservative government could give secondary schools more league table points if a greater proportion of their pupils take so-called 'harder' subjects such as maths and science.
The Tories have announced that they may consider reviewing the current league table system to reward schools that encourage pupils to take subjects regarded as tougher, rather than those topics perceived to be easier, like media studies.
Michael Gove, the shadow education secretary, told the BBC's Andrew Marr Show that the current system, which ranks schools on the number of GCSE grade Cs that pupils achieve, is unfair because it does not take into account the different subjects being taken.
"The truly brighter students aren't being stretched because there's no emphasis on getting people from a B to an A or an A to an A*," he claimed.
He also claimed the system means that teaching staff do not focus on the weaker students who would benefit most from greater attention.
However, a spokeswoman from the schools department told the news provider: "We simply don't recognise the labels 'soft' or 'hard' A-levels - all subjects are rigorously measured against each other to maintain standards."
Meanwhile, a new report into the development of the 14-19 diploma in schools has suggested more training is needed for teachers taking the courses.
The Ofsted report has argued the current teaching standards are falling short, with many teachers having never undertaken this style of education in the past.