The UK's leading universities are as "exclusive as ever" and are not trying hard enough to attract poorer students, an expert has said.
Top institutions should follow the lead of their counterparts in the United States and be clear that they want their student populations to represent wider society, according to Bahram Bekhradnia, director of the Higher Education Policy Institute (HEPI).
Research shows that the proportion of poor students attending the most selective and prestigious universities in the country - such as Oxford and Cambridge - has not changed in 15 years, and might even had fallen, he said.
Giving HEPI's annual lecture, Mr Bekhradnia said the rise in numbers of students from poorer families going to university had been almost entirely down to "less prestigious" universities.
Unlike many other countries, the UK has a "highly stratified - even hierarchical - university system", he said, adding: "The university you attended makes a difference to your life chances."
Institutions at the top are highly academically selective in the students they take, and performance in school is closely linked to background.
"Posh students go to posh universities because they do better at school and less posh students to less posh universities because they do less well at school," Mr Bekhradnia said.
"The hierarchy and its causes are well-known to students when making their choice of university."
He went on to say that Russell Group and 1994 Group universities, which he described as "the most research intensive and prestigious", are "as socially exclusive as ever".
"I don't think that there is snobbery or explicit bias, but nor do I think that they try hard enough.
"In the USA the top universities explicitly engage in social engineering and are clear that they seek to represent wider society as far as possible in their student population, while maintaining high academic standards."
In the UK, universities will avoid anything that could be seen as "social engineering", Mr Bekhradnia said.
"They need to do better. Their gesture in favour of increasing fair access is that they are beginning to look at what they call 'contextual' information about why students from poor backgrounds may have performed less well at school than others.
"That is a start, but they need to go further and be explicit that they aim to have a better social mix in their universities."
Mr Bekhradnia used the lecture to warn that the UK's success in offering people a second chance at an education may be under threat by the overhaul of university funding - a move that saw fees for English universities treble to a maximum of £9,000 a year in 2012.
Figures have shown that the number of part-time students has plummeted since the hike.
"In terms of offering second chances to people who may have missed out on higher education straight after leaving school, we undoubtedly have performed well," he said.
"Unfortunately, these are the very things that are most at risk as a result of the recent increases in fees."
Mr Bekhradnia also repeated concerns about university standards, saying that there are differences in the amount of time students spend studying at different institutions and that a survey of European students had revealed that 38% found the courses here to be less demanding than their home country courses.
"Why should this be? Why has teaching apparently become neglected and expectations lowered so?"
He suggested it might be because universities are focusing on research at the expense of teaching.
"Research takes time and effort and staff are under great pressure - student-staff ratios are no better than in other countries - and I fear an unspoken conspiracy between staff and students. Staff saying to the students, 'we won't make a large demands on you, if you leave us to get on with our research'."
Mr Bekhradnia said it is important that the standards issue is addressed.
"If it becomes widely known that some degrees are much easier to obtain than others then that will damage the reputation of the universities concerned, and similarly if it becomes known that degrees from English universities can on the whole be obtained with significantly less effort than degrees from elsewhere then that will damage our system as a whole.