Science deans this week warned Charles Clarke, the education secretary, that allowing popular non-science degrees to charge lower fees than unpopular science courses could cause irreversible damage.
Ian Haines, chair of the UK Deans of Science Committee, told The THES that most university science heads wanted to charge the maximum £3,000 top-up fee for science.
Mr Clarke told a Commons debate last Thursday that it might be sensible for universities to charge a much lower fee for struggling science courses to attract more students.
The deans, who met Mr Clarke this week, are unwilling for science courses to be wholly dependent on cross-subsidy from more popular subjects.
They said they were concerned that if the government allowed other courses to charge less, applications to study science subjects could drop to even more dangerous levels and this might lead to further department closures.
In keeping with Mr Clarke's position, at least one Russell Group university is understood to be considering running a free physics degree to attract applicants and avoid closure. However, this solution was greeted with much anger by many scientific bodies.
Professor Haines said: "I find that the daftest idea imaginable."
He warned that in the long term, university councils would tire of subjects such as business studies subsidising subjects such as physics.
Phillip Diamond, higher education policy adviser at the Institute of Physics, said: "You would not want people to do your subject because it was cheap. Physics is a subject that presupposes a certain amount of aptitude."