The prime minister has continued his push to persuade Labour MPs to back him in next week's vote on university top-up fees.

Following a series of meetings with potential rebels on Tuesday, Tony Blair gave an interview to Wednesday's Guardian newspaper in which he dismissed claims that a new top rate of tax could solve the higher education funding crisis as a "myth".

Ministers insist that the only viable option for reform is their package of variable tuition fees of up to £3,000 per year coupled with maintenance support for the poorest students.

"If you take the amount of money that - on paper - you would raise from top-rate taxpayers, the myth is that this is the amount you would raise," Blair said.

"But every single piece of analysis that has ever been done indicates that what would actually happen is that large numbers of those taxpayers - probably the wealthiest - would simply hire a whole lot of new accountants to do this and that.

"And actually your tax take would be a lot less."

The prime minister argued that the issue was central to his belief that Labour needed to reform public services before the Tories get the chance to privatise them completely.

"University education is fundamental to the future of the country," he said.

"We know there is a funding gap. We also know we need to get more of our young people going to university, especially from poorer backgrounds.

"If progressive politics can't provide a fair answer to that challenge, we will simply repeat the mistakes of Labour governments of the past."

He added that students and families from middle class backgrounds would also benefit from the Higher Education Bill.

"They will pay nothing on the way through university and their child pays [later] on a pretty fair basis," he argued.

And he claimed that he was winning the battle to convince over 100 backbench critics that the top-up fees proposal was the "right" thing to do.

Blair also went on to insist that the £3,000 cap would not need to rise.

"I do believe that the longer this has gone on, the more people have realised it is, at best, the right policy and, at worst, it is at least highly arguable that it is the right policy," he said.

"If you look at Australia and New Zealand, they have a cap and the same arguments were made there. But they have not scrapped the cap."

However wavering MPs may also be swayed by a MORI poll released on Wednesday showing that four out of five students would have reconsidered their choice of university if variable fees had been in place.

With backbenchers concerned that poorer students may be "priced out" of the best courses, the survey showed that the deterrent effect of top-up fees would have been higher among state educated pupils than those from the private sector.

The poll also showed that students predict that they will graduate owing an average £9,341 of debt even before the extra fees are levied.

But education secretary Charles Clarke said the findings disproved "ridiculous" claims of future graduate debt of £30,000.

"Around 90 per cent of students in the survey say that the money they spend is a good investment in their future and 95 per cent think going to university is a worthwhile experience," he said.