England's top universities have been given a dressing down by the Government's higher education tsar for suggesting that there is a limit on the numbers of poorer teenagers they can recruit.
The argument that these youngsters do not get high enough grades "just doesn't hold water", Les Ebdon, director of the Office for Fair Access (Offa) said as he urged institutions to work with schools to ensure that pupils get the results they need to apply.
The Russell Group, which represents 24 of the UK's most selective universities - including Oxford and Cambridge, has previously said that disadvantaged teenagers are becoming more likely to go to one of its institutions, with many bursaries and financial aid available, but that children from disadvantaged backgrounds are under-achieving at school and getting poor advice and guidance.
In a guidance note to universities and colleges on access agreements, Prof Ebdon said he expected universities to set out clearly how they are working with schools to raise attainment.
This could include, where appropriate, sponsoring schools and academies to help raise standards faster.
Prof Ebdon said: "There are more young people from disadvantaged backgrounds in higher education than ever before.
"While this is extremely welcome, there is much more to be done to ensure that someone born in a disadvantaged area is as likely to enter higher education as someone born in an advantaged area.
"One of the key ways universities can make a real difference is to ensure that they are working hand-in-hand with schools to make sure that aspirations and attainment can be raised in our disadvantaged communities.
"For some time, a number of universities - especially those with the highest entrance requirements - have told me that there's a limit to what they can do to improve fair access because people from disadvantaged areas secure - on average - lower entrance grades.
"I'm afraid this argument just doesn't hold water. It is precisely because there are lower rates of attainment in disadvantaged areas that universities must work in close partnership with schools to raise attainment.
"Indeed, there are many examples of universities already working closely and creatively with schools and I expect to see much more of it.
"Raising the attainment of young people from disadvantaged backgrounds is crucial, and I want it to be a major part of the access plans of universities.
Under the current fees system, any English university wishing to charge tuition fees of over around £6,000 must have an access agreement approved by Offa.
This sets out what the university intends to do to recruit and retain youngsters who would not normally study for a degree.
A Government spokesman said: "We want the whole sector to work with us to improve the quality of schools, so that more students of all backgrounds have the grades and the confidence to apply to the best universities, and be successful in their exams in the first place.
"So we welcome this decision by the Director of Fair Access as an important first step towards creating thriving university-supported schools in every part of our country."
Russell Group head of policy Sarah Stevens said: "Professor Ebdon is right that working with schools is one way universities can support raising attainment and that is exactly what Russell Group institutions are doing.
"Many of our members already have extensive partnership and outreach programmes with schools that are designed to encourage successful applications from all backgrounds.
"We estimate that the 24 Russell Group universities work with well over 2,000 schools, reaching many tens of thousands of students across the UK every year.
"Our Informed Choices guide provides free advice to pupils on course selection to help ensure talented pupils have every chance to apply to a leading university and this year Russell Group members in England alone will spend more than £250m to help widen access."