Some academics have joined students in opposing the plans

John Prescott told the BBC's Breakfast with Frost programme that opponents of the plans had "real justification".

Some 159 MPs have signed a Commons motion against top-up fees and the vote in January on the Higher Education Bill could end in Tony Blair's first defeat.

The bill allows universities to charge students up to �3,000 a year.

Sensitivities

But Mr Prescott hinted that ministers may be preparing a compromise on their controversial plans.

He told interviewer David Frost: "At the moment, we are in active dialogue. We recognise the sensitivities that our people have - and they do have real justification for some of those arguments.

"We must argue it through and I say let's wait and see, until the day it comes to a vote."

Education Secretary Charles Clarke is holding a series of meetings with critics in a bid to win them over.

We recognise the sensitivities that our people have - and they do have real justification for some of those arguments Deputy Prime Minister John Prescott

Unconfirmed reports suggest the education secretary may be preparing to offer an increase in the �4,000 loans students are allowed to borrow or to raise the �15,000 salary threshold from which they will start to repay fees.

But there seems to be no sign of change on the key issue of whether universities should be allowed to charge variable fees up to a limit of �3,000 a year, which critics argue will lead to a two-tier system.

The government argues the new system would be fairer because students would no longer have to pay tuition fees, currently �1,250 a year, up front.

I very much hope that the government will stick to its guns and get this through Chris Patten, former Tory party chairman

Mr Prescott compared the top-up fees issue with the part-privatisation of air traffic control, which he said had faced backbench opposition in Parliament but had proved successful.

Former Conservative chairman Chris Patten, speaking on the same programme, criticised his party's policy of scrapping tuition fees and cutting numbers of students.

Mr Patten, who is chancellor of both Oxford University and the University of Newcastle-upon-Tyne, said the party should not be arguing for a cap on fees.

"I very much hope that the government will stick to its guns and get this through, because there is nothing else on offer to the universities," he said.

Shadow education secretary Tim Yeo told BBC Radio 4's World This Weekend that Labour's top-up fee proposals would damage universities' independence and burden students with debt.

But Conservative former higher education minister Robert Jackson, who supports top-up fees, said his party's policy was "irresponsible" and would make universities suffer.