University tuition fees have risen nine-fold in the past six years, but students are only getting 20 minutes extra a week with lecturers as a result, according to new research.

The study raises fresh questions about standards, revealing that on average an undergraduate at an English university spends about 900 hours a year on their studies, around 300 hours less than recommended by the university watchdog.

Studying for a degree at an English university is still "more like a part-time than a full-time job", according to the Higher Education Policy Institute (HEPI), which co-authored the report.

The study also highlights stark differences between institutions and between courses in the amount of time students spend with lecturers, and suggests that some undergraduates are studying for less than half the hours of their peers.

The 2013 Student Academic Experience survey, produced by HEPI and Which?, questioned thousands of students at UK universities for their views of their courses.

The findings show that the total student workload - both time spent in lectures and private study - now averages about 30 hours a week, equivalent to around 900 hours for each 29-week academic year.

This is around 25 per cent less than the 1,200 hours suggested by the Quality Assurance Agency, the study says.

HEPI's report on the survey says: "In our previous report we commented that study at an English university was more like a part-time than a full-time job, and so it has proved again."

The survey also shows that since the first HEPI Academic Experience survey was conducted in 2006, just before tuition fees rose from £1,000 to £3,000, the amount of "contact hours" - time spent with academics in lecturers and seminars - has risen by just 20 minutes a week.

During this same period, fees have risen nine-fold from £1,000 a year to a maximum of £9,000 a year at English universities.

Students are getting just eight minutes extra with lecturers compared to 2007, when fees were £3,000 a year.

HEPI's report on the survey says: "There is no sign that as students pay more they are receiving more for their money, and that is reflected in a sharp increase in the proportion of students who feel that they are not receiving good value for money."

Around three in 10 first-year students at English universities, the first group to face fees of up to £9,000, say that they do not think their course offers value for money, the survey found.

The survey does reveal that students generally believe that they are putting more effort into their studies, spending 14 hours and eight minutes on average on private study, over an hour more than in 2006.

The survey shows wide differences in the amount of time students spend working towards their degree.

Undergraduates at some universities are studying for around 20 hours a week in some subjects, and others are working more than double that.

HEPI's report on the survey says it is "disquieting" that different universities can make varying demands of their students in the same subject, and raises questions about comparing standards in different universities.

The issue should be seriously addressed, according to HEPI.

It said: "If it becomes known that is is 'easier' to obtain a qualification in one university than another, then that will in due course damage the reputation of that university, but it will also have an impact on the reputation of the entire UK higher education system."

The survey shows that different subjects can have different amounts of "contact time". For example, students taking science-based degrees are likely to spend more time in the laboratory with academics, while arts students could spend more time on private study.

But the results also reveal differences across each subject.

At one university, medical students were spending an average of 32.7 hours a week studying, while those at another were working for 49.8 hours.

In maths and computer sciences, the amount of time a student spent studying ranged from 23.1 hours a week to 44 hours.

HEPI director Bahram Bekhradnia said: "There is an information point here. We do think students need information about how much contact they're getting and why they're getting it. There may be an answer to why you're only getting three or four hours of contact a week, but I think that needs to be clearer to students."

He said what was more "interesting and disturbing" was the differences between study hours within subjects.

"Although the average amount of study for a student taking law is about 30 hours a week, there are some students that are doing just over 20, and some that are doing getting on for 50 hours a week," Mr Bekhradnia said.

"This does raise profound questions about relative standards, what's going on here? Can we claim that a student in one university that does half as much work to get a degree as a student in another university - what does it say about those establishments, is it plausible that they've achieved the same outcomes by the end of their studying?"

While there may be plausible explanations, this needs to be investigated, he added.

Which? executive director Richard Lloyd said: "With an increasingly competitive higher education sector, and soaring tuition fees, it has never been more important for prospective students to get as much information as possible to help them make the right choice.

"There must be an investigation into the huge variations in the academic experience that we have revealed, and more transparency to ensure students can get the information they need."

A spokeswoman for the Department for Business, Innovation and Skills said: "We want the best possible match between students and institutions. People must be able to make informed decisions about what and where to study.

"That's why we introduced the key information set, which compares a range of data at course level on costs satisfaction and outcomes. Institutions should explain to prospective students how their course will be delivered in order to help them make the right decisions."

Nicola Dandridge, chief executive of vice-chancellors' group Universities UK, said: "The increase in fees means that students are clearly demanding more from their universities. But it is misleading to make a crude assumption that time spent in lectures and seminars can be equated with university course quality. UK university education places an important focus on supporting independent study which will vary from course to course and between individual institutions.

"Tuition fees also pay for far more than contact time. They cover all manner of services including student support facilities, employment advice and training, library services and clubs."

She added that it is essential that students understand what their university offers, and insisted that institutions are working hard to provide prospective students with more information.

Sally Hunt, general secretary of the University and College Union (UCU), said: "It is perhaps not surprising that some students and their parents expect more bang for their increased buck, following the rise in university fees. Frustratingly, despite the hike in fees, universities are not any better off after the Government slashed state support for higher education.

"Staff and universities simply cannot do more for less and if we are to maintain a world-class university system, producing satisfied graduates ready to tackle the challenges of the future, then we have to accept that costs money. Higher education remains something this country can do well, but it needs proper investment."

Dr Wendy Piatt, director-general of the Russell Group, which represents 24 leading universities including Oxford and Cambridge said: "Students are right to expect value for money - that's why our leading universities place so much emphasis on high-quality teaching and learning and investing in cutting-edge facilities.

"Millions of pounds have been invested in new books and labs, improved lecture theatres, innovative teaching, more professional careers services and smaller class sizes.

"However, the independent learning required at university is a very different experience from learning at school, so it is important we take the debate away from the narrow confines of contact hours.

"The workload is rightly demanding at Russell Group universities; students are supported through their studies in different ways and learn in ways that are hard to quantify."