Attempting to clarify his remarks, Mr Johnson said that it was “utterly ludicrous and infuriating” to suggest that he believes women attend university in order to find a husband.
He insisted that he was merely pointing out that when a large number of students are female, you intensify so-called “assortative mating” – whereby people choose to choose a partner similar to themselves.
“Some people seem to have misconstrued something I said at a press conference five days ago, about relative male underachievement in university entrance,” Mr Johnson said.
“It is utterly ludicrous and infuriating to suggest that I think women go to university to find a husband. I was merely pointing out something that I’ve said several times before – that with a graduate cohort 68 per cent female you intensify the phenomenon sociologists identify as assortative mating.”
Kate Green MP, Labour’s Shadow Equality Minister, called on Mr Johnson to apologise for his “outdated opinions”.
“Boris Johnson may think his buffoonery allows him to get away with his outdated opinions but this isn’t funny,” she said.
“These comments are insulting to the women across the country and across the world who have gone to university, worked hard and used their talents to get on. He should apologise.”
The Everyday Sexism campaign group tweeted that the remarks were “pathetically archaic, unacceptably sexist and hopelessly out of touch”.
A City Hall source said that Mr Johnson’s comments were “off the cuff” and said they were “clearly intended as a joke”.
“He does not, of course, think that at all,” the source said. “It was completely light-hearted. It has been misconstrued.”
Mr Johnson met his first wife, Allegra Mostyn-Owen, while studying classics at Oxford.
Mr Johnson last month described David Cameron as a “girly swot” because he got a first class degree in Philosophy, Politics and Economics at Oxford.
The Mayor of London got a 2:1 degree from Balliol College.