The concession may appease some Labour MPs who oppose more fees

Charles Clarke told the Sunday Telegraph the government was determined to allow universities in England and Wales to charge higher tuition fees.

But he said some students could be helped out by bursary or fee remission schemes.

"It is to make sure that students from the poorer families are able to go to the universities which are charging the highest fees," he said.

"It is conceivable that there will be a zero fee for students from certain families with low incomes."

Currently, universities charge a flat �1,125 a year for all undergraduate courses.

Ministers want to allow institutions to charge "differential fees", as they call them, of between nothing and �3,000 a year for their courses.

The fees would be in the form of a loan paid back by students upon graduation, rather than paid upfront as they are now.

'Easier entrance'

Mr Clarke said he had not yet decided the income threshold below which students would be completely exempt from top-up fees.

But it could be that students will qualify if their family's household income is less than �15,200 a year.

That is also the threshold which will be applied for the new �1,000 student maintenance grants which are to be reintroduced from next year.

The move is being seen as a concession to Labour MPs opposed to the higher fees, ahead of the debate on the legislation which is due to come to the Commons in December.