British universities are taking a hard look at changes to their admissions procedures for undergraduates, after evidence that significant numbers of disadvantaged and ethnic minority students are dissatisfied with the current system.

A survey of university applicants commissioned by vice-chancellors and seen by the Guardian found that many black and other ethnic minority candidates, as well as those from families without a history of studying in higher education, complained of obstacles during their applications, including poor careers advice and a time-consuming process.

The poll of 1,500 recent applicants to higher education, conducted by Savanta ComRes and commissioned by the Universities UK (UUK) group, found that fewer than two-thirds said the system works well, with black and minority ethnic applicants the most likely to support a radical overhaul such as a shift to applications after A-level grades are published.

Julia Buckingham, the vice-chancellor of the University of Brunel University London and president of UUK, said: “On the whole university admissions are seen as fair but all students must have faith in the system and receive careers advice to help them make the best decisions about what and where to study.

“It is the job of universities, colleges, employers, schools and the government to work together to fill the gaps in good quality careers advice for applicants, and particularly to disadvantaged groups.”

The survey was commissioned by the group representing 137 universities in England, Scotland, Wales and Northern Ireland for its admissions review group that is considering recommendations to improve the system.

The Office for Students, the higher education regulator in England, is conducting its own review of admissions, a move endorsed by the education secretary, Gavin Williamson, who said: “I am glad the OfS is looking at whether it would be in students’ interests to apply for their university place after they have their A-level results.”

Most students receive offers of places that are conditional on achieving certain A-level grades, based on the grades predicted by their teachers. But critics say grade predictions are notoriously unreliable, and conditional offers leave students and universities in the dark for several months.

The survey found that 64% agreed the process “works well as it is”, but more than half backed making major changes that would upend the timeline of applications, offers and acceptances being made in winter before pupils sit A-levels in the spring and receive their results in the summer.

Fifty-six per cent said universities and colleges should make offers only after receiving students’ results, and the same proportion backed a more radical shift to begin applications after A-level results, “even if the term started later”.

Students who were the first from their families to apply to higher education, and those from black and ethnic minority backgrounds, were more likely to support post-A-level admissions.

While 70% of applicants agreed the current process was fair, 12% disagreed, complaining about poor career advice and lack of information, with some alleging the system was “biased towards upper and middle class applicants”. Black and minority ethnic students were less likely to rate the application process as fair.

Ucas, which administers the admissions process for undergraduates, was ranked as the most-used source of information by 38% of students, with parents and guardians cited by 35% and school teachers by 34%. Universities were used as prime sources by only 27% of students.

Clare Marchant, the chief executive of Ucas said: “It’s welcome news that most students agree the current application process is fair, and that the clear majority of applicants felt supported when applying, particularly by Ucas.”

Marchant said her organisation was “already exploring innovative reforms to the admissions process, including how changing when students receive offers could bring benefits”.