Undergraduates in England spend less time studying per week than their European counterparts, a report says.
Universities say it is quality not quantity that counts
The Higher Education Policy Institute surveyed 15,000 first and second year students. It found they averaged 26 hours of teaching and private study.
The survey showed workload variations between subjects but also within the same subject at different universities.
Vice-chancellors' group Universities UK said length of study provided no information about degree quality.
The think tank's survey found that students were offered 14.2 hours of teaching per week on average.
The range was from just over 20 hours to 8.4 hours.
'Down the pub'
The highest levels of study were said to be in health, science and engineering subjects and the lowest in social science and the humanities.
The three subjects with the lowest hours of teaching - historical and philosophical studies, linguistics and social studies - had less than half the level of teaching of the most heavily taught subject, veterinary and agricultural science.
In addition, the amount of private study ranged from 16.5 hours a week among those on architecture, building and planning courses to 9.5 hours in mass communications and documentation.
The average was 12.5 hours.
A separate survey, Eurostudent 2005, collates comparable data on the socio-economic background and living conditions of students throughout Europe.
Those taking their first degree in Germany typically spend nearly 35 hours per week in total studying, and in Portugal it is about 40 hours per week.
The director of the institute, Bahram Bekhradnia, said there was also a marked gender difference in the amount of studying that students did.
"Boys are down the pub and the girls are in the library, you can characterise that as," he said.
In a commentary on the survey findings, Prof Graham Gibbs said 20 hours a week was part-time studying.
"So a significant minority of UK students are enrolled full-time but studying part-time, with their university receiving funding for full time students, and this phenomenon is the norm in some subject areas."
Part of the phenomenon of lower student effort might be cultural, he said.
He said in mainland Europe students on average undertake between 8-15 hours a week of paid work, whilst studying full time - compared with 33% of UK students undertaking more than six hours of paid work a week - and still, on average, put in more study hours than in the UK.
The director general of the UK's Russell Group of research-led universities, Dr Wendy Piatt, said different learners required different levels of input.
"The Russell Group of universities admit high-achieving, well-prepared, self-motivated students and we encourage them to work effectively and efficiently through directed self-learning.
"The combined teaching and world-class research environment at our universities ensures that we continue to produce capable, self-motivated, innovative graduates of the highest standard."
But Hepi said its findings were "potentially very serious".
"Although there is no suggestion here that the length of study equates to quality of learning, as these comparisons become better known there is bound to be increasing pressure on English universities to explain how their shorter, less intensive, courses match those elsewhere in Europe.
"These findings, together with the finding reported later in this report that a worrying proportion of international students believe they receive poor value for money, and the fact that fees in this country are so much higher than in most other countries, make our international student market vulnerable.
"A decline in that market could seriously impact the finances of a great many universities."