A graduate tax or a system where students pay extra fees back after their course are the main options for boosting future university funding, the education secretary has said.

Charles Clarke said students may still be asked to pay "hundreds" of pounds in advance to go to university.

But he said it would not be the thousands of pounds that some colleges have been talking about, echoing the words of Tony Blair.

Thousands of students protested about student debt and the prospect of higher fees in a rally in London on Wednesday.

We are not going to put levels of fees up front that would inhibit people from access to university from poorer backgrounds

Charles Clarke

Undergraduates already have to pay annual upfront tuition fees of up to �1,100 at all universities in England, Wales and Northern Ireland.

It is feared increasing those costs will deter poorer students from entering higher education.

On Wednesday the prime minister tried to calm the speculation surrounding the idea of allowing some universities to charge top-up tuition fees after Downing Street acknowledged cabinet splits on the issue.

Insisting the "status quo is not an option", Mr Blair refused to rule out top-up fees to ease the burden on cash-strapped universities.

	:	Student protest
Thousands take to the streets

But Mr Clarke told the BBC Two's Newsnight: "The government isn't split at all.

"We are not going to put levels of fees up front that would inhibit people from access to university, in the future, from poorer backgrounds."

But Mr Clarke added that the final decision would not be announced until January.

Tuition fees 2002-03

Nil if parents' income less than �20,480 Sliding scale up to �1,100 on incomes over �30,502

"We are still discussing the situation in detail."

Asked if the choice was between a graduate tax paid throughout people's lives or students paying back a "theoretical loan" over a set period, Mr Clarke replied: "It's in that field, those are the two main options as they have to be logically."

The level of the fees and how they might vary between courses also had to be considered, he said.

On Wednesday, Tony Blair told MPs the government's review would "increase access to universities. It will not mean parents are having to pay upfront thousands in fees."

But Mr Clarke insisted no decisions had been taken and that parents might still be asked to pay "hundreds" of pounds up front.

The minister also said the government would also look at research funding for non-mainstream degrees, following criticism of "frivolous" courses - including golf course management and aromatherapy.

Oxford Student Union president Will Straw, the son of foreign secretary Jack Straw, who joined Wednesday's protest, told Newsnight he was confident top-up fees would not now be introduced.

Mr Blair was "clearly listening to students", added Mr Straw.

The prime minister's comments are being seen as a retreat for Mr Blair, who has been seen as a fan of allowing top universities to charge higher tuition fees.

But Mr Clarke has previously rejected reports that Downing Street was "wedded" to the idea.