England's top universities have made "little or no headline progress" in recruiting students from poorer families in recent years, a watchdog has warned.
Despite making a considerable effort and spending millions of pounds, the performance of these selective institutions has remained flat, according to a new report by the Office for Fair Access (OFFA).
It suggests that this group of universities must do more to offer activities and schemes that will help to boost the numbers of disadvantaged students going into higher education.
In his foreword to the report, OFFA Director Professor Les Ebdon warns that an "unacceptably large" gap remains between the numbers of rich and poor students attending leading universities.
OFFA's annual report, issued jointly with the Higher Education Funding Council for England, examines the performance of England's universities in widening participation, such as offering bursaries and fee waivers as well as "outreach" activities such as summer schools and master classes for teenagers.
The findings, for the year 2011/12 - the final year before tuition fees were tripled to a maximum of £9,000 - shows a mixed picture.
It reveals that universities spent more than a billion pounds in total on widening participation in 2011/12.
Universities charging over the basic tuition fee, which in 2011/12 was £1,345, must sign an access agreement setting out how they plan to recruit more students from disadvantaged backgrounds. They must also spent at least part of the income they get from charging above this fee on this area.
The latest report shows that institutions spent £444.1 million of their higher fee income on bursaries and outreach activities in 2011/12, compared to £424.2 million in 2010/11.
But the report also shows that while this has gone up in cash terms, universities actually spent a slightly smaller percentage of their extra income from tuition fees compared to the previous year.
OFFA insisted it was not concerned by this, as it had been predicted the year before and was down to the global economic situation, uncertainty about funding and institutions preparing for the new fee system.
The amount of money spent on widening participation from funds other than higher tuition fee income fell to £624 million from £645 million the year before, the report shows.
Separate figures show that overall spend on outreach activities alone fell by £17 million in 2011/12.
This was partly because universities had to alter the way they worked after the Aimhigher scheme, which saw universities and schools working together to encourage young people to go into higher education, ended, the report said.
Prof Ebdon said that most universities had met or exceeded the targets they had set for themselves to recruit more students from disadvantaged backgrounds.
But in his foreword he adds: "It's not a wholly positive picture.
"We know that, despite their considerable efforts, the most selective institutions have made little or no headline progress in increasing access in recent years."
In future these universities are being asked to spend more money on widening participation and on the activities that are "most effective" at boosting recruitment.
Prof Ebdon adds: "Universities and colleges must get smarter in their investment if we are to maintain the improved participation from disadvantaged groups to the sector as a whole and start to close the unacceptably large participation gap between advantaged and disadvantaged people that remains at our most selective universities.
"Where you come from is still much too closely related to where you will end up, and universities and colleges have a vital role in helping change this."
Today's report is Prof Ebdon's first as OFFA director. At his pre-appointment hearing last year, he told a cross-party group of MPs that he was prepared to use tough sanctions, such as fines or withdrawing funding agreements, for universities that fail to meet targets on recruiting and retaining disadvantaged students.
He said he would be prepared to "press the nuclear button" if institutions do not meet tough targets.
Dr Wendy Piatt, Director General of the Russell Group, which represents 24 leading universities, including Oxford and Cambridge said its instiutions are committed to ensure its doors are open to talented students.
But she added: "We face real difficulties as we seek to make rapid progress on achieving demanding and quite specific targets.
"There are complex socio-economic problems which mean students from disadvantaged backgrounds all too often fail to achieve the right grades in the right subjects or do not apply to selective universities. Our universities put a lot of effort into trying to help solve these problems but we cannot do so alone."
Business Secretary Vince Cable said: "I have always said that going to university should be about ability, not ability to pay. So it's encouraging that the National Scholarship Programme has helped more than 35,000 students from poor backgrounds in its first year. This has been supported by over £130 million investment from Government and institutions."
The report shows that in 2011/12 14.8 per cent of full fee-paying students at Cambridge University - 1,607 in total - were in receipt of full state support, meaning they were from households with incomes of less than £25,000.
At Oxford, 14.3 per cent of students - 1,443 in total- were in receipt of full state support.
Around 79.5 per cent of the students at the University of East London were from homes with an income of less than £25,000 - 9,478 students in total, and at the University of West London 2,733 students (61.1 per cent) were in this group.
A Cambridge University spokesman said: "Since this reporting period, which relates to 2010 entry, the University has made significant steps towards our key milestone of increasing state sector admissions without compromising academic standards.
"In September 2012, 63.3 per cent of our UK first years came from the state sector, the largest proportion for thirty years. This exceeds our original objective and reflects attainment in UK schools."
Liam Burns, president of the National Union of Students (NUS), said: "The fantastic work of students' unions around the country has protected cash support for many students and in some places managed to turn the tide against useless fee waivers.
"Even so, less money is reaching students' pockets through government and universities than it was in 2010 despite rising living costs and the increased student commitment that comes with higher tuition fees."