The Government is facing a legal challenge to its plans to raise tuition fees to up to £9,000 a year.
Lawyers are planning to seek a judicial review of the decision on the grounds it contravenes human rights law because it could discriminate against poorer pupils.
The legal firm Public Interest Lawyers said it was bringing the case on behalf of two sixth-formers, Callum Hurley and Katy Moore, who would be due to start university when the rises come into force in September 2012.
PIL said it had sent the Business Secretary, Vince Cable, a "pre-action protocol letter" about the rises – seen as the first step to seeking a judicial review.
The legal firm's action coincides with a request from Gareth Thomas, Labour's shadow universities spokesman, to the Universities minister David Willetts, to spell out details of any further cuts to university budget if too many universities opt to charge the maximum £9,000 figure.
Mr Willetts has indicated that he believes £9,000 should only be charged in "exceptional circumstances". However, all members of the 20-strong Russell Group are expected to seek to charge the maximum. Ministers have made it clear the Treasury has only budgeted for an average £7,500 loan to be paid to students to help them meet the cost of the fees.
If the average is higher, it could mean further cuts to university budgets.