The number of poorer students to attend one of the country's top universities has fallen in the past decade.

Out of the 24 Russell Group universities, Oxford had the lowest proportion of entrants from lower social backgrounds at one in 10.

Ten years ago, poorer students made up around one in eight Oxbridge entrants.

Oxford said it has legally binding targets which work towards and focus on categories of disadvantage rather than school type or self-reported socio-economic class.

Universities minister, Jo Johnsonm said: "These figures underscore a worrying lack of progress at some institutions and underline how vital it is that highly selective universities redouble their efforts to reach out to students from disadvantaged backgrounds.

"There is still much more to do to boost social mobility, which is why we plan to legislate for a new transparency duty to shine a spotlight on university admissions processes."

Around one in six (17.2 per cent) students from lower social groups started a course at a Russell Group institution last year compared with nearly one in three (32.1 per cent) of their wealthier peers.

In comparison, disavantaged students make up more than a third (37.5 per cent) of entrants to other UK universities. 

The results are based on data on social classes published by the Higher Education Statistics Agency (HESA) for the past 10 years. HESA has announced it is discontinuing the social classes measure.

Wendy Piatt, director-general of the Russell Group, said: "Ensuring our doors are wide open to talented and able students from all backgrounds really matters to us and real progress is being made.

"While our universities invest a huge amount of time, effort and resources into improving the situation, they cannot solve this problem alone.

"There are still far too many children from disadvantaged backgrounds underachieving at school and receiving poor advice and guidance."