Two-thirds of 16-year-olds may be put off attending university by the introduction of top-up fees, a national poll has found.
The Liberal Democrat survey of nearly 2,500 pupils taking GCSE courses in 311 schools, some of whom would be the first to pay top-up fees in 2006, found that 67 per cent felt higher fees would affect their decision to attend university.
The survey shows that the prospect of accumulating debt would have a greater impact on pupils from poor backgrounds - even among those who thought they would qualify for a grant.
Out of half of the pupils surveyed who believed they would be eligible for financial aid, 76 per cent said that the possibility of debt would affect their decision to go to university.
The level of fees charged by different institutions and the cost of particular courses would also influence most pupils' choices.
The survey found that 69 per cent of pupils planned to factor into their decisions how much different institutions charged. More than half said fees would affect which course they enrolled on.
Liberal Democrat education spokesman Phil Willis, who commissioned the poll, said the survey presented "damning evidence that Labour's policy would hit students from poorer backgrounds hardest".
He added: "British students should not have to choose their university by how much they charge.
"Poorer students will naturally choose cheaper universities, while only rich pupils will be able to afford the more expensive."
Another survey published on Thursday says that parents will carry the real burden of student debt. More than one in seven people said they would work overtime to put their child through university, while 9 per cent said they would find a better paid job.
Parents would also be prepared to remortgage their house (6 per cent) or send stay-at-home partners out to work (4 per cent), according to research for Insight Investment, the asset manager arm of the Halifax and Bank of Scotland group.
Nearly one in five parents (19 per cent) wants their children to go to their local university and live at home to reduce costs, rising to 22 per cent among people on lower incomes.
And 16 per cent of those questioned said they would advise their child not to go to university but to get a job instead.
National Union of Students national president Mandy Telford said: "Students without parents who are in a position to help them financially will be hit the hardest. Increasing student debt and student hardship will return university to the privilege of the wealthy."
Liberal Democrat leader Charles Kennedy will claim that Labour's policies have reduced the proportion of students from the two lowest economic groups in higher education from 17 per cent when it came to power to 8 per cent today.
He was due to tell a Liberal Democrat gathering in Westminster on Thursday that their party would tackle this by using £700 million out of £4 billion raised through a new top rate of income tax to abolish tuition fees and reintroduce grants.
He was expected to say it was time for a "fundamental and radical change" in the post-compulsory system involving breaking down the divide between further and higher education.
The Liberal Democrats would create a modularised further and higher education system that would allow students to accumulate credits through any mode and level of study.
More money would be ploughed into developing foundation degrees, he said.
Some courses such as media studies and golf course management, which the Conservatives had said they would scrap, would be converted into foundation degrees.