An annual £760 shortfall in funding for every sixth form college student has been uncovered as a result of a government spending freeze combined with spiralling costs.

Research by the thinktank London Economics says funding for ages 16-19 education in sixth form colleges has declined by 22% in real terms over the past eight years, resulting in cuts to staff, curriculum and enrichment activities.

For the first time, the consultancy has calculated the additional funding it says is required per student per year in order to deliver an internationally competitive sixth form education.

The report, which was commissioned by the Sixth Form Colleges Association (SFCA), says an additional £760 per head would ensure there were adequate student support services, protect subjects that are under threat and allow for three additional hours of extracurricular activities.

There are more than 160,000 students studying at sixth form colleges – meaning a total funding shortfall of £122m a year – and the sector is responsible for almost 25% of all the A-levels taken in England each year.

Teachers and parents have campaigned to highlight budget cuts in primary and secondary schools, but the Institute for Fiscal Studies highlighted last month the fact that funding for sixth form and further education (FE) students had been been cut much more sharply than any other area of education.

According to the new report, sixth form colleges received £1,380 less in real terms per student in 2016-17 than they did in 2010-11. The number of teachers has been cut by 15%, while the number of students has gone up by 6%.

Peter Cooper, the principal of Hereford sixth form college, said sixth form education in his area, which is largely rural, had been particularly badly hit, with school sixth forms closing, students being taught for just three days a week, and languages and science being axed from the curriculum.

“I am fortunate to run a large, extremely successful college which has so far managed to weather this storm and maintain a high quality offering and range of extracurricular activities,” he said. “But I fear for the future of all our young people if this campaign for fair funding for this age range is not successful. I hope our politicians and civil servants listen before it is too late.

“Our 16- to 19-year-olds are a key age group and, I would argue, are even more important for our social and economic future than those going to university. These young people should be prioritised, as other countries do, rather than given the short straw in the education system.”

Bill Watkin, the SFCA’s chief executive, said: “It is now well understood that sixth form education has experienced deeper funding cuts since 2010 than any other phase of education. But until the publication of today’s report, the impact of cost increases has been less well understood.

“The debate about sixth form funding now needs to move from how much funding has been cut to how much funding is actually needed to provide the sort of high quality, internationally-competitive education that our young people deserve.”

The apprenticeships and skills minister, Anne Milton, said the government had protected the base rate of funding for 16- to 19-year-olds until 2020, but added: “However, I am very aware of the funding pressures. We will continue to look carefully at funding for the sector in preparation for the next spending review.”