The full effect of fees is still being assessed

The National Institute of Economic and Social Research spoke to 4,000 third year students at four universities.

It found the average student would owe about �15,000 at the end of their course, compared with recent estimates for current students of �9,744.

But the government says 90% of students see the fees - which could rise to �3,000 a year - as a good investment.

"We are getting rid of upfront fees and proposing to offer the poorest students a minimum of �3,000 a year," a spokesperson for the Department for Education and Skills said.

Disabled students

However, the NIESR report said the satisfaction level might decline.

Researcher Hilary Metcalf said increased costs so far had led to a slight increase in those who had regrets about having gone to university.

The average student in our sample would have debts of around �15,000 at the end of their course, nearly triple that of students prior to fees Hilary Metcalf

But this appeared to be due mainly to a change in the sort of students - towards those who were more likely to have regrets about higher education in general.

Higher costs had the biggest effect on those "where financial disadvantage was already present" - with the impact on debt being greater for disabled students, probably because they were less able to work to pay their bills.

These effects were among those students caught by the initial introduction of a �1,000 fee in 1998.

The report's suggestion of total debt of �15,000 upon graduation compares with the latest estimate from current students, from this week's Unite/Mori survey, of about �9,744 - a rise of 54%.

'Highly predictable'

Ms Metcalf said: "It seems safe to say that student debt and term-time working increase and more students will live at home. These are highly predictable.

"However, the research also suggests that the increase in debt could be substantial. Our finding that, on average, the full fee cost was passed into debt means that the same cannot be ruled out for top-up fees.

"In this case, the average student in our sample would have debts of around �15,000 at the end of their course, nearly triple that of students prior to fees.

The National Union of Students said the government was "attempting to sell top-up fees to students by spinning a line that being in debt is acceptable".

"What this survey does is to contest the government's claim that poor students will be better off under top-up fees, because they have supposedly 'introduced the grant'," said its president, Kat Fletcher.

"A grant is not a grant if there are fees attached to it."

Conservative higher education spokesman Chris Grayling said loading young people with debt would have "dire consequences" for public services.

Liberal Democrat spokesman Phil Willis said polls suggested his party was the first choice for students and "it is clear that Labour will be held to account at the ballot box for their U-turn over top-up fees."

Paying for university: the impact of increasing costs on student employment, debt and satisfaction, by Hilary Metcalf, published in National Institute Economic Review No. 191.