More than a third of UK universities have given up offering specialist modern European language degrees over the past 15 years, the Guardian has found, as leading academics argue harsh marking at A-level is putting teenagers off studying the subject at school.

Since 1998, the number of universities offering French, German, Italian and Spanish as single honours degrees or jointly with another language has plunged by 40% and the rate of decline has increased in recent years.

The number of universities offering degrees in the worst affected subject, German, has halved over the past 15 years. There are 40% fewer institutions where it is possible to study French on its own or with another language, while Italian is down 23% and Spanish is down 22%.

The result is that languages are increasingly elite subjects, studied at an ever decreasing number of top universities. "If this rate of decline continues, two or three language departments will close every year and the remaining students will have a lot less choice," said Michael Kelly, head of modern languages at Southampton University and former adviser to both the coalition and Labour governments on modern languages.

"These findings confirm that the UK has in recent years been systematically squandering its already poor linguistic resources," said Katrin Kohl, professor of German at Jesus College, Oxford and director of the Oxford German Network.

"We're reaching the position where language competence is a prerogative of the privately educated elite, and language degrees are restricted to Russell Group universities."

The data has been derived from an analysis of Ucas course listings for 1998, 2007 and the forthcoming 2014-15 entry – which shows a steep and accelerating decline in institutions that provide specialist language degrees.

The last government scrapped compulsory languages at GCSE level in 2004. Falling numbers of degree courses reflect a decline in the number of pupils taking traditional modern foreign languages at A-level – the total is at its lowest since the mid 90s. This summer only 6.9% taking French, German and Spanish achieved A*, a lower proportion than other subjects, prompting a major inquiry into how modern language A-levels are marked.

But academics worry the inquiry itself may deter even more students from taking an A-level in a modern language unless a new marking structure is in place by next year's exams. In a letter in Tuesday's Guardian, leading academics warn that unless more is done to shore up languages in secondary schools, the closure of language departments could escalate still further.

"Modern languages departments in schools are under pressure from management because the subject is unfairly perceived to be underperforming," the group writes. "University departments of modern languages struggle to recruit students because A-level uptake is falling and candidates are missing their offers.

"The disadvantaging of modern languages candidates in school examinations has been blighting the subject at all levels, and will continue to do so until the unfair grading is addressed effectively. Gifted linguists discouraged by poor results drop the subject after GCSE. Some of the brightest linguists are wary of choosing modern languages at A-level for fear of losing out on top grades and university places."

However, while specialist language degrees are being cut, anecdotal evidence suggests degrees with other subjects that involve a language component, such as law and French or business studies and Spanish are stable.

Beginner and intermediate language modules that are not part of students' main degrees are also growing in popularity, university sources say, although comparative figures are not available.

No Northern Irish or Welsh university offers Arabic or Russian degrees, while outside England, Japanese is only available at Cardiff and Edinburgh. Although Chinese is growing in English universities, it is not available in Northern Ireland at all and only Bangor, Trinity St Davids, Heriot Watt and Edinburgh provide degrees in the subject in Wales and Scotland.

"Students already face fewer choices if they want to study languages," said Sally Hunt, general secretary of the University and College Union, the trade union that represents university lecturers. "If we continue down this path there will be whole swathes of the country where students simply won't be able to study languages," she added.

The analysis shows a continued concentration of language degrees at top universities. Of the 24 institutions that have cut language degrees since 2007, most were newer universities. For the remaining single honours courses, three quarters of Italian courses, two thirds of German and half of French and Spanish studies degrees are at the elite group of Russell Group universities. Even so, only 12 Russell Group universities still offer single honours degrees in all four main European languages: French, German, Italian and Spanish.

David Willetts, the universities minister, said: "The last government marginalised languages in schools. This government is reversing the decline. Language learning at GCSE is now at its highest level for five years."A DfE spokesman said: "We are addressing the chronic lack of attention paid to foreign languages in schools. For the first time ever, we have made it compulsory from September 2014 for primary schools to teach a language so that children can learn this crucial skill from a young age.

"Young people can then build on that at secondary school. Including foreign languages in the EBacc is already having an effect. The number of students studying languages at GCSE rose by more than 15 per cent last year – and is now at its highest level for five years. We fully expect this to have an impact on future A level numbers."

Additional reporting by George Arnett