Leading Scottish scientists have joined the battle over the future of Britain, raising fears that separation could result in a loss of vital funding.

The SNP hits back today with student support for its promise to pay off their loans and abolish the graduate endowment.

The exchange follows a warning in The Herald from one of Scotland's leading university Principals that manifesto pledges are putting higher education at risk.

Support for the Union has come from some of Scotland's best-known academics, including Professor Ian Wilmut, creator of Dolly the Sheep, cancer researcher Professor Sir David Lane, microbiologist Professor Hugh Pennington and Sir Kenneth Murray, who developed the hepatitis B vaccine.

In a letter to The Herald, the 62 leading scientists have said they are "very concerned" that the constitutional debate has shown no consideration about Scottish science. The letter states: "Separation would inevitably lead to disruption of these ties with detrimental consequences for the health of the Scottish science base and for the long-term viability of the Scottish economy and society".

The SNP responded with an endorsement from Professor Stephen Salter, a renewable energy engineer at Edinburgh University. He said: "Funding does not depend on borders but rather the quality of the applications and maintaining competitive edge".

While Labour promises nearly £285m extra in higher and further education funding from 2008-11, the SNP has offered £60m more over the next four years, £10m extra reserved for research, a Life Sciences Institute in Dundee and a £5m Saltire Prize for innovation.

LibDem leader Nicol Stephen pledged £168m extra each year. He also favours ending the graduate endowment and boosting grants.

In Glasgow, Chancellor Gordon Brown followed up on the scientists' letter in a Labour campaign speech. He said: "Far from being a barrier to invention, the United Kingdom has been the framework that has helped Scots create the inventions and find the cures which have built our name around the world".

The SNP campaign to highlight support from different groups in society moves on to students with an advertisement in The Herald today.

The party promises an end to the graduate endowment and paying off student loans, while Labour pledges not to introduce top-up fees, as in England, while retaining the £2100 graduate endowment.

Alex Salmond commented: "In recent years student debt levels have soared, with thousands of our youngest and brightest starting their work life with an £11,000 debt burden. That is the wrong approach for Scotland. It's time to dump that debt with the SNP".