Universities employ 88 people who earn the same as the First Minister's £140,000 salary or more.

Just two principals across the 18 institutions earn less than the leader of the Scottish Government, according to figures from the National Union of Students (NUS).

University of Edinburgh employs 52 people on or above £140,000 a year, with other top salaries at the universities of Aberdeen, Glasgow and Strathclyde.

Aberdeen principal Sir Ian Diamond earns the most, £303,000, according to the figures.

Robin Parker, president of NUS Scotland, said: "It's unjustifiable for university principals and other senior staff to routinely be paid such large sums.

"There are 88 senior staff members at Scottish universities who earn more than the First Minister, and across our institutions the gap between the lowest and highest paid is too large, with some receiving almost 20 times that of the lowest paid university employee.

"Universities need academic autonomy but they should not have the freedom to pay such large salaries and to allow large gaps between those at the top end and the lowest paid. There are hundreds of millions of pounds of public money quite rightly going into universities over the next few years. We must make sure that this money is used on the frontline, not on increasing already-substantial senior salaries."

The details were in a submission from the NUS to consultants developing the governance code for universities.

NUS wants a maximum pay ratio between high and low earners.The largest ratio at present is at Abertay Univeristy where the highest earner gets 19.9 times more than the lowest paid worker. The average ratio across Scottish universities is 16.1, the figures show.

Across the sector, average pay before pension contributions and benefits in kind is £200,000. It rises to £240,000 after pensions and benefits.