A university with one of the worst PhD completion rates in the UK has admitted that some of its candidates are not suitable for doctoral study - particularly international students who lack an adequate level of written English.
The University of Derby, which began offering doctorates in 1992, was one of 10 institutions contacted by the Higher Education Funding Council for England last summer and asked to explain why such a low proportion of full-time PhD students were completing within seven years and part-time students qualifying within 10 years.
In his response to Hefce - obtained by Times Higher Education through a Freedom of Information request - John Coyne, Derby's vice-chancellor, laid the blame on lax admissions criteria.
"The university must not just take students because they express an interest in research and are qualified," he wrote.
A report written by Paul Bridges, Derby's head of research, adds that there are "some indications" that not all Derby's doctoral students have "the necessary aptitude, knowledge, understanding and commitment to undertake original research, together with the required skills of communication".
"There is no point in taking more (PhD) students if 60 per cent will ultimately fail to complete, as they do currently...A low completion rate will lead to poor reputation, and that, in turn, will lead to weaker applicants," he writes.
He highlights particular concerns about the standard of Derby's overseas students, whose completion rates have "fallen significantly in recent years".
"There have been several instances where I have concluded the student has simply not been good enough," he says.
He goes on to warn that Derby's completion rates will deteriorate further over the next two cohorts, with the university "still haemorrhaging significant numbers of students who have not completed".
However, in a statement to THE, Professor Bridges says he is confident that a new "risk-based approach to admissions", including tougher language testing, will improve Derby's performance from 2012-13.
There have been "some encouraging signs" in the current academic year, with only a third of the withdrawals seen in 2009-10, he adds.
Professor Bridges also admits that the "large differential" between the fees paid by home and European Union students (currently £3,465 a year) and overseas students (£8,880 a year) means there is "a financial interest in attracting suitable international doctoral students".
One senior sector figure, who did not wish to be named, said the "limited linguistic and cultural competence of international students" was a big issue for many UK universities, with standard tests of English failing to provide a "good guide to writing skills".
"There is also pressure from funders, especially some Arab and Asian governments, to admit students direct to PhD tracks without a probationary master's year," the source added. "It is then much harder to downgrade students (to) a lesser qualification if they are not really capable of achieving PhD standard without their supervisors effectively writing large chunks of their theses."
However, Malcolm McCrae, chair of the UK Council for Graduate Education, emphasised that the number of PhD students at the 10 underperforming universities was relatively low, and warned against conveying a false impression that foreign research students were likely to receive "poor treatment" if they came to the UK.
Meanwhile, Michael Brown, vice-chancellor of Liverpool John Moores University, one of the institutions under scrutiny, criticised Hefce for assessing it against benchmarks based on the requirement of research councils and charities that the PhD students they fund complete within four years.
Professor Brown said his institution had a high proportion of self-funded students whose "personal circumstances" required slower working, or who were studying purely out of personal interest and for whom "time is not necessarily of the essence".
"There is no rational reason why the needs of (such students) should not be facilitated," he said.
Many of the universities' responses to Hefce set out measures they have undertaken to improve completion rates, with a number citing the enhanced monitoring of supervisors. The University of Sunderland said it intended to refer cases that give "cause for concern" to its pro vice-chancellor for research - although it admitted that this was "a contentious issue".
In its response, the London School of Hygiene and Tropical Medicine pointed out that its low recorded completion rates were the result of clerical error.
The other institutions contacted were City University London, De Montfort University and the universities of Bedfordshire, Brighton, Gloucestershire and Huddersfield.
In a statement, Hefce says it is satisfied with all the responses.