Delegates at the Trades Union Congress (TUC) in Brighton heard that fees of up to �3,000 a year would leave students from working-class backgrounds with debts of up to �20,000.

Paul Mackney, leader of the lecturers' union Natfhe, said only "dimmer and dimmer members of the upper classes" would end up as undergraduates.

He urged the TUC to join the National Union of Students' demonstration on October 26.

'Same as other countries'

The conference motion came after 170 Labour MPs publicly opposed the proposed charges, known by their enemies as "top-up fees.

The Commons is due to vote on the government's plans this autumn.

Meanwhile, higher education minister Alan Johnson is expected to say taxpayers cannot be expected to pay the entire higher-education bill.

Other countries already accept this, he will add when he addresses the vice-chancellors' group Universities UK at Warwick University.

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

Ministers say this does not reflect the varied cost and value of higher education provision.

Allowing institutions to charge between nothing and �3,000 a year will also allow them to fund an expansion of student numbers to around half of young people by 2010, they say.

Last week, Universities UK president Ivor Crewe Professor Crewe angered the NUS leadership when he said graduates earning �18,000 would only have to pay fees back at the rate of �5.20 a week, or the price of a couple of pints of beer.