Medical schools have failed to find alternative funding for undergraduates who want to study for an extra year.
The option, open only to the brightest students during their degrees, has been dashed by the Medical Research Council's sudden withdrawal of funds.
Deans of medicine say the MRC's emergency decision was announced too late for them to meet the deadlines of charities and other possible sources of funding for students who had been planning to start the extra year in October 1996.
The science year, known as the intercalated year, enables the top medical students to learn about research. It is seen in medical academe, which is suffering from both university and NHS cost-savings, as a way of nurturing the next generation of medical researchers. It leads to a BSc.
The MRC has funded about 160 places a year. Jane Lee, director of corporate affairs, said: "We took an emergency holding decision. It isn't that we don't think they are important but we are trying to make sure that we are putting money for clinical training in at the right level".
Medical school deans fear that the cut may be extended further than one year. Ms Lee said that the MRC is reviewing all its commitments to research training. "It may be that we should be concentrating on fellowships, senior fellowships and so on instead."
At Manchester University, Roger Green, dean of medical undergraduate studies, said that 30 out of about 240 students a year are expected to intercalate, with ten funded by the MRC. More than 60 students apply to intercalate and all gain at least an upper second.
"We have tried for other sources of funding but because of the way that it was withdrawn we haven't had much opportunity to do anything," said Professor Green.
Frank Harris, dean of medicine at Leicester University, said the move was "a major knock. Where the devil are our future clinical academics going to come from?"