The study - Are Scottish Degrees Better?, by Professor Robert Wright, chair of economics at Stirling University, and Mark Taylor of Essex University - found that graduates with a Scottish degree earned an average of pound;15 an hour while those with an English degree were paid pound;17.50 - a difference of pound;5,200 a year.
Taking into account other factors affecting earnings, the wage gap grew to 46 per cent. Professor Wright said: "The conclusion you could draw is that somehow English degrees are better and employers are willing to pay more for that."
He believes that with 50 per cent of young Scots now in higher education, "relative to our immediate competition, the type of students going to university aren't up to the job. They should be educated at a more skills-based level.".
John Downie, leader of the Federation of Small Business in Scotland, called on Scottish universities to become better at making graduates more ready for work.
Robin McAlpine of Universities Scotland said: "This is a problem in the minds of employers not in the quality of graduates."
One suggestion is that the figures may be skewed by the recruitment practices of major companies. "It's a case of 'blue chip' on the shoulder," one source said.