English students could be charged as much as £6,500 a year to attend a Scottish university under plans outlined by the Scottish National party today.
Scottish ministers fear that measures in London to allow English universities to charge students up to £9,000 a year will dramatically increase the number of "fee refugees".
Under the Edinburgh plans, Scottish students and students from other EU countries would still have all their tuition fees paid by the state. But English students could be charged more, in part in an attempt to address a deepening funding gap at Scottish universities.
These measures will only be introduced if the SNP regains power in May's elections, when higher education funding is likely to be a contentious issues.
Scottish university principals believe the English funding deal will increase competition for the best students and academics, further eroding the status of the "ancient" institutions such as Edinburgh, St Andrews, Glasgow and Aberdeen, and weakening their position internationally.
The devolved government has cut the direct funding of universities by £67m next year with further reductions to come, forcing many to sack teaching staff and drop courses, after its spending was cut by the UK Treasury.
About 22,500 English students currently study at Scottish universities and pay annual fees of £1,820, or £2,895 for medicine. There are 11,895 Scottish students at English colleges.
Labour in Scotland came out tonight in favour of graduates paying a fee or contribution after they find work, making common cause with the Tories, the umbrella body Universities Scotland, and the Scottish government's own council of economic advisers.
Mike Russell, the Scottish education secretary, said his government believed access to higher education should be based solely on "the ability to learn, not the ability to pay". He said that "was at the very heart of what I believe and what the SNP believes".
Russell's green paper on higher education funding set out six options, which he said would be costed before the election.
It also suggested that to cut costs universities may have to merge or share administration staff, offer "private" education to those who can pay, look for more donations, and drop courses which are duplicated by other universities.
Lawyers from the Matrix Chambers in London have warned that charging students in England up to £9,000 a year was contrary to human rights law because it discriminated against students from poorer backgrounds.
