Education experts raised fears over the future of Latin in schools, warning that teachers were telling their pupils to avoid the subject because it is too hard.

Academics at Durham University found that Latin is about a grade harder than any other subject at GCSE.

Will Griffiths, director of Cambridge University's school classics project, said the fact that Latin is seen as difficult represented one of the biggest threats facing the subject nationally.

"We know teachers who want their students to do Latin, but say to their students, 'in all honesty you have more chance of getting an A if you do French.'

"It comes down particularly to league tables," he said.

Less able students "simply just won't enter the exam at all".

Boris Johnson, shadow higher education minister and an author on Roman history, condemned the trend. "It is pathetic," he said. "Latin is a wonderful subject that introduces you to the roots of European civilisation. It is a fantastic foundation for all kinds of careers. I never regretted doing it for a moment.

"It would be the worst possible outcome if kids were directed away from Latin just because it is difficult."

Latin and Greek virtually disappeared from state schools after the introduction of the national curriculum in the 1980s. However, independent schools continued to teach the subject.

Mr Johnson said it should be openly acknowledged that some subjects are harder than others and pupils should be given credit for taking more difficult courses.

"If we pretend the A-Levels are the same and all A-grades are the same we are lying to the kids so they are endlessly switching to the soft options. "It would be absolutely tragic if Latin were to be further dumbed down in order to encourage people to take it," he said.

"Teachers have got to have a bit of guts and get people to do difficult subjects."

Dr Robert Coe at Durham University's curriculum, evaluation and management centre, analysed a figures for 600,000 students.

He compared the grades they achieved in each subject. The results showed that at grade C, Latin was about a grade harder than the next hardest subjects which tend to be sciences and modern languages.

Latin is about three grades harder than some other subjects such as sociology, the study found.

Dr Peter Jones, co-founder of Friends of Classics, a society for Latin and Greek enthusiasts, said the major problem was the lack of adequately qualified new Latin teachers.

"The main reason why there are so few (exam) entries is because there are so few state schools doing it," he said.

"There are only about 35 teachers a year who are allowed to be trained in classics and there are more jobs than there are teachers.

"This is an extraordinarily difficult situation."