Changes to teacher training is fuelling a shortage of potential maths and science teachers, according to a new report.
Universities UK (UUK) has raised concerns about the impact of the government's decision to give schools more say in the recruiting and training of staff. It says that if the pace of this change continues, it could create problems in training enough teachers.
Since 2012/13 initial teacher training has undergone a radical shake-up, with an increasing number of training places going to the new School Direct programme, rather than universities.
Under School Direct, schools take the lead in taking on would-be teachers and training them. However, this has led to "instability" for many universities, with the numbers of training places allocated directly to institutions falling by 23% in three years.
The report goes on to warn that these changes have an effect on the supply and quality of teachers available to teach subjects that are important to the economy and economic growth.
Official figures show that School Direct managed to fill just two thirds of its allocated places in 2013/14, while universities filled over 90%, the study found.
The teaching profession relies heavily on universities to train chemists, physicists, mathematicians, computer scientists and modern linguists, UUK says.
While School Direct has been more successful in recruiting trainee English and history teachers, it has been less successful for science, technology, engineering and maths (Stem) subjects.
"This has contributed to a shortfall in the number of trainee teachers recruited into several subject areas, such as mathematics and physics," the report says.
"There are concerns, therefore, that, as the government pursues its ambition for a school-led system, the pace of change could create teacher supply issues in the future if university-delivered training becomes unsustainable."
UUK called for universities to be given greater stability over teacher training, and for higher education's role in the system to be recognised and clearly defined.
Malcolm Trobe, deputy general secretary of the Association of School and College Leaders (ASCL), said: "ASCL has been raising concerns for more than a year over teacher recruitment. While the system is working in places, a significant number of schools say they are having real issues recruiting suitable applicants. The shortfall is serious and although the report highlights Stem subjects, we know there is an issue across a wide range of subjects including English and maths.
"Although the previous system wasn't perfect, one advantage it did have was an overall plan to ensure that there were enough teachers coming through in every subject. The problem now is that there is no overall picture of recruitment and retention. Going forward, there needs to be a coordinated plan for recruitment that can anticipate demand for teachers in specific subjects or regions of the country."
Sally Hunt, general secretary of the University and College Union, said: "This report's findings prove how dangerous a path the government is taking as it sidelines university teacher training courses. For the first time next year, School Direct trainees will outnumber university teacher training students yet it isn't even filling all its places.
"If politicians persist with this policy, university teacher training departments will be in grave danger, despite being the engine houses for the next generation of maths and physics teachers that our schools and economy so desperately need."
A Department for Education spokesman said: "We recognise the importance of recruiting top quality candidates in subjects like maths, chemistry and physics. That is why we are delivering generous tax-free bursaries and prestigious scholarships worth up to £25,000 for these core subjects.
"We know that schools are particularly keen to attract the highest calibre trainees. School Direct is an increasingly popular teacher training route with the number of applications rising by more than a third year on year. Universities will continue to play an important role in teacher training, working closely with schools to shape and deliver training and continuous professional development."