The government is concerned about a growing gender gap in higher education, after 22,500 more young women than men won places at university last year.
Last year, 57% of first degree graduates were women
Ministers fear men will struggle to get good jobs in future as growing numbers of teenage boys decide against degrees.
In evidence to an inquiry by a committee of MPs, the government said progress at getting more working class students into college was tailing off.
Since September, students are being charged tuition fees of £3,000 a year.
In a document sent to the Commons education select committee, the government said: "Gradual progress has been made in broadening the social mix of the student population, but progress has been slow and there are signs that it may be starting to level off.
"The social class gap in participation remains the biggest single issue, although we are increasingly concerned about male participation."
More women graduates
Ministers have set a target to get 50% of young people into higher education by 2010.
Figures last year showed 47% of 17-30 year-old women had gone into higher education by 2004, compared to 37% of young men.
And last year, 57% of first degree graduates were women.
The Higher Education Funding Council for England (Hefce) warned that university, once dominated by young men, was becoming increasingly the preserve of women.
Hefce chief executive Professor David Eastwood said: "It matters in the sense that it mattered when it was the other way around.
"The wider worry is that if we are not careful we are going to arrive at a position where young lads are alienated, they are under-skilled and, given everything we say about the nature of the knowledge economy and the premium that will be placed on graduate skills, they will find themselves disadvantaged in the labour market."
But he dismissed the idea of gender quotas for university places to address the problem.
"We need to understand better why this is happening and start taking some action sooner rather than later."
Higher Education Minister Bill Rammell said the government was working hard to widen participation.
He said research showed that boys who achieved well at school were just as likely to go to university as girls.
This was why our work at school level to improve boys' attainment is so important, he added.
"In the Pre-Budget Report, the Chancellor announced an additional £10 million in 2007-08 to develop more effective guidance to schools on improving boys' attainment and in addition the DfES has introduced a number of strategies to address the gap in gender achievement and to raise the performance of all pupils. "