Scotland's universities stand to lose £210m a year in research funding if the country becomes independent, Liberal Democrat leader Willie Rennie has claimed.
Mr Rennie said investment in the sector, which saw £234m awarded to research projects in Scotland from UK sources for work in new technologies, could "dry up".
The Scottish Government dismissed his comments as "Tory-style scaremongering" and insisted that Scotland's "unrivalled record of success" in attracting funding was secure.
Mr Rennie said figures showed Scottish universities punched above their weight in the research sector, winning 14% of available funding from UK sources despite Scotland having 8.5% of the UK population.
The data from the Higher Education Statistics Agency (HESA) showed Scotland received £130m from UK-based charities, £100m from the UK Government and £47m of funding allocated to UK universities by industry, commerce and public corporations.
He said: "Scotland is at the cutting edge of research and development work in the UK. Our universities are doing work which is producing technologies which the applications for could almost be limitless.
"The expertise exists in Scotland, but we could not do all of this exciting new research without the extra bonus funding that we receive from across the border.
"The real danger of splitting Scotland from the UK is that you also split our universities from this vital source of funding which helps to fuel the innovation."
But Education Secretary Michael Russell said Scotland's universities enjoyed a "global reputation" and would continue to attract investment if they were part of an independent nation.
He said: "This year alone, we are investing £289m in research and knowledge exchange through the Scottish Funding Council. This is expected to lever in an additional £500m from Research Councils, Europe, charities and business.
"We are building on this success for future success, and working with the sector and others to ensure greater access to those sources and other external funding streams.
"While the SNP are delivering for Scotland, all that the Liberal Democrats can do is indulge in Tory-style scaremongering."