THE Scottish Government is under pressure to publish legal advice suggesting universities could continue to charge fees to students from the rest of the UK after independence.

The call comes from a group of pro-Union academics who have reiterated existing concerns that the fees would be unlawful in the event of a Yes vote in this year's referendum.

EU law prevents undergraduates from European countries outside the UK being charged fees by Scottish universities because they have to be given parity with home students - who have their tuition paid for them.

EU law does, however, allow different fees regimes to operate in higher education in countries that are part of the same overall political structure, such as the UK.

However, if Scotland were to become independent, it seems likely students from the rest of the UK (rUK) would have to be treated like European students and be given free tuition.

Despite this, the Scottish Government's White Paper on independence proposes keeping the current arrangement if Scotland votes to leave the UK.

The campaigning group Academics Together - part of the Better Together campaign - urged the Scottish Government to publish any legal advice it had received on the issue.

Niamh Nic Shuibhne, professor of European Union Law at Edinburgh University, said: "The Scottish Government would face an extremely steep uphill battle to convince the EU institutions that it should be entitled to retain a practice involving systemic direct discrimination against one particular cohort of EU citizens."

A report by Academics Together added: "Even if the numbers of students from elsewhere in the UK stayed at the same level as today, this would represent a loss of income to Scottish universities of £150 million.

"If the numbers were to increase - and there would be a very strong incentive for young people from England to come to Scotland for a free education - the effect could be even greater."

A Scottish Government spokesman said the White Paper was consistent with, and informed by, legal advice the Government had received.

He said: "The content of any legal advice is confidential. By long-standing convention, successive Scottish and Westminster governments have not disclosed the source or content of legal advice other than in the most exceptional circumstances."

The legal advice is understood to be based on the same argument as advice obtained by Universities Scotland last year which suggested ministers could still justify charging fees because universities here would be swamped with rUK students escaping high fees.