Middle class students were more likely to get a place at their preferred university this year, research by the Sutton Trust has found.
72 per cent of pupils from wealthy families said they were accepted at their top choice university compared to 63 per cent of their less well-off peers, according to a new report by the social mobility charity.
Researchers examined the role of predicted grades in the admissions system and whether it gives an advantage to students from richer backgrounds.
In general those from better off backgrounds do better in exams than their peers and so would be more likely to achieve the grades required to secure a place at their first choice university, the Sutton Trust said.
But they also noted that in the "chaos" of this year's exams, children from wealthier backgrounds might have had better support to navigate the system, particularly those whose parents know more about the system.
A poll of 500 university applicants found that working class teenagers were more likely to say they would have applied to a more selective university if they had known their A-level results when making decisions.
Sir Peter Lampl, founder and chairman of the Sutton Trust, said: "The utter chaos of this year's university admissions exposed major flaws with the system that are due principally to our reliance on predicted grades."
He argued that moving to a post-qualifications admission system, where students apply to university after receiving their A-level results, would benefit "high achieving low-income students as their grades are often underpredicted".
This summer, A-level grades were awarded based on teachers' predictions after a controversial algorithm was ditched.
But only 38 per cent of applicants received grades that matched their teachers' predictions, the Sutton Trust report found.
32 per cent of students from state schools said they were underpredicted by teachers, compared to 26 per cent of those from private schools.
University lecturers backed a move to a post-qualification admissions system, saying that the current one is "not fit for purpose".
Jo Grady, general secretary of the University and College Union, said: "This report shows students are receiving university offers according to inaccurately predicted results, with students from more affluent backgrounds more likely to gain a place at their preferred university than their less affluent peers.
"Allowing students to apply after they receive their results will help level the playing field, remove the problems associated with unconditional offers and end the chaotic clearing scramble." Universities UK, which represents vice-Chancellors, is currently reviewing university admissions and is due to report on its findings later this year.
"The review group is analysing the evidence and views of applicants towards predicted grades, unconditional offers and post-qualification offer-making, and exploring ways in which those from disadvantaged backgrounds can be better supported throughout the process," they said.