Research student numbers could fall in England as a result of a funding formula to be introduced next year, a think-tank said this week.
The Higher Education Funding Council for England has announced a streamlining of postgraduate research student funding, bringing three strands into one.
It has allocated an extra £60 million to ensure that no university loses out.
But the Higher Education Policy Institute analysed this policy against a report by JM Consulting, commissioned by the council, on the true costs of supervising and training research students.
Bahram Bekhradnia, director of Hepi, was due to tell a Universites UK conference on postgraduates this week: "The JM Consulting report has so far had little publicity. This is surprising given it shows that the costs of training and supervising these students is far higher than previously thought."
JM Consulting said: "Current funding for each student varies considerably, but is well below the levels of cost, leading to significant levels of under recovering of costs, almost without exception."
Hepi figures show that, typically, the cost of supervising and training each postgraduate student is 49 per cent more than a university gets from funding and research councils.
This shortfall rises to 79 per cent for those students not funded by the councils.
Mr Bekhradnia was expected to say that the shortfalls were on top of the extra £60 million.
"Universities may decide that it is no longer economic to take students without financial support from the Higher Education Funding Council for England or the research councils," he said.
Rama Thirunamachandran, Hefce director of research and innovation, said:
"We are just one of a number of funders of postgraduate education.
"We have recognised a shortfall in funding and done our bit to rectify it.
I do not see how an increase in funding will lead to a fall in numbers."
Under the new formula, only departments rated 4 or above in the research assessment exercise will receive funding for research students - although there are limited funds in areas where the council is trying to build a research base.
The council also decided that research student numbers would no longer be used to help determine how much research block grant universities received.
Tom Sastry, researcher at Hepi, said: "The formula has changed the incentives and we are yet to see what effect this will have on behaviour."
The Future of Postgraduate Education at the Barbican, London, is sponsored by Universities UK.