SCOTLAND'S university principals have called for an expansion of undergraduate places amid fears that a national drive to recruit bright pupils from poorer backgrounds will force out other students.

Universities Scotland, which represents the principals, backs Scottish Government aims to widen access but argues ministers have to fund extra places in the long term to prevent greater competition in a system that is already oversubscribed.

Currently the middle classes dominate higher education and access initiatives have only gone a small way to redress the balance.

However, as the Scottish Liberal Democrats have highlighted, introducing a new stream of students from working-class backgrounds will displace other socio-economic groups unless the system is expanded.

The call - just days before tens of thousands of Scottish pupils get their exam results - comes after the Scottish Government made it a priority for universities to improve rates of participation by pupils from deprived backgrounds after a decade of stagnation.

All institutions have been tasked with improving access under new outcome agreements with the Scottish Funding Council, with those that fail facing a reduction in funds.

This year, the Government announced £3.5 million to pay for more than 700 extra places to kick-start the initiative, but universities are concerned these numbers will not be funded in future.

Universities Scotland also wants to see a commitment that any future expansion of access students will also be accompanied by extra funded places.

Alastair Sim, director of Universities Scotland, said: "Scotland's universities fully support widening access to people of all backgrounds who have the potential to benefit.

"Funding new access places, as the Scottish Government has done this year, is a sensible and welcome way to help universities widen access as it avoids creating additional competition amongst students for a place at university when demand already outstrips supply.

"Widening access has to be a long-term commitment and we'd like to see the additional places for this continued on a sustainable basis into the future."

Mr Sim stressed the importance of an expansion given the "high demand" for a university education from both Scots and applicants from the EU.

"Without a modest expansion of places this year, there was a risk that the goal to widen access to university could have added further pressure to what is already a highly competitive situation. We are pleased to see this has been avoided and hope this model continues in future," he added.

The call was backed by student body NUS Scotland. Its president, Gordon Maloney, said: "While we've seen record numbers of Scottish students applying to our universities, the fact remains the poorest students are still most likely to lose out. The creation of extra university places, including those ring-fenced for widening access, is vital to ensure we provide more opportunities to access a degree and, if demand continues to increase, we need to consider increasing these places further."

Angela Constance, Minister for Youth Employment, said the Government intended to build on the expansion of higher education that has taken place this year.

"We know that widening access to university will take more work and a generational change and the measures in the Post-16 Education Bill put widening access agreements on a legal basis to kick-start this change."

Earlier this year, Scottish Liberal Democrats warned many Scottish students would miss out on university places because of Government moves to widen access.

Liam McArthur, the party's education spokesman, said legislation backing greater recruitment of students from poorer backgrounds would displace other socio-economic groups.

The UCU lecturers' union also warned universities could face legal action if they chose students on the basis of background rather than academic achievement.