Nobel prize-winner Professor Joseph Stiglitz said education is "one of the most important contributors" to growing inequality in the US, claiming many poorer young people cannot afford to get a degree.
A leading economist has voiced his concerns about university tuition fees in England.
"What is going on in England is a source of concern," he said.
Prof Stiglitz, a member of the Scottish Government's Council of Economic Advisers who has advised both the French and US governments in the past, spoke out on the issue as he addressed MSPs at Holyrood.
Scottish students do not pay tuition fees if they are studying for a degree at a university in Scotland.
But official figures published last year showed that a third of English institutions will charge students the maximum £9,000 as standard for a degree beginning in autumn this year.
Around three in four universities in England will charge the top rate for at least one of their undergraduate courses.
Prof Stiglitz, from Columbia University in New York, said that in the US, incomes are falling while university tuition fees were rising.
Addressing the Scottish Parliament's Economy Committee, he said: "Median income, income in the middle, real income is stagnating, going down. But, meanwhile, the cost of college education is going up.
"With incomes going down and tuition going up that means that many, many children of poor families will not be able to afford a university education. And you need, in the 21st century, a university education to compete."