Queen's University Belfast has hit back at criticism that only per cent of its students come from working-class backgrounds, saying it needed the income from top-up fees to maintain its level of resources.
Sinn Fein has said that the 30-point gap between the percentage of students from upper-middle class families and working-class families would have to be closed.
The party, whose senior negotiator Martin McGuinness was the province's education minister and who is now suspended along with the rest of the power-sharing administration, said that Queen's vice-chancellor George Bain's support for national education minister Charles Clarke's plans for top-up fees would lead to Queen's becoming part of a two-tier third-level education system.
Belfast's Republican Lord Mayor Alex Maskey and fellow assembly member Michelle Gildernew argued that this was dangerous, "given the reality that we have only two universities within the north".
But Queen's said that if it were denied the resources it needed to maintain its position "more of our brighter young people will leave to study elsewhere".
"Students from poorer backgrounds, who may not have the option of leaving, will be seriously disadvantaged by not being able to attend a world-class teaching-and-research university in their own region," a statement said.
At present, 40 per cent of Queen's students do not pay fees, and a further 20 per cent pay reduced fees because of low levels of parental income. The university has a range of scholarships and bursaries, and has launched a fundraising campaign to increase student back-up support.