Nearly half of state secondary teachers never or "rarely" advise their academically gifted pupils to apply to Oxford or Cambridge universities, new research has found.
A poll commissioned by the Sutton Trust also found that 79 per cent of the teachers thought ex-state-school pupils comprised less than half of Oxbridge students. The actual proportion is 57 per cent.
And nearly a third of the 730 teachers polled by the National Foundation for Educational Research thought state pupils comprised less than a fifth of the Oxbridge intake.
Sir Peter Lampl, chairman of the Sutton Trust, a charity that campaigns for greater social mobility, described the results as "deeply concerning". "The sad consequence of these findings is that Oxford and Cambridge are missing out on talented students in state schools, who are already under-represented at these institutions based on their academic achievements," he said. "We need to do much more to dispel the myths in schools about Oxbridge and other leading universities."
But Mary Bousted, general secretary of the ATL education union, said: "Teachers might have some very legitimate concerns about whether an academically gifted pupil would fit in and thrive in Oxford or Cambridge. I was in a Cambridge college last week and it oozed wealth and privilege. I didn't feel entirely comfortable there, so how would somebody feel if it was totally alien to their upbringing?"
A breakdown of the poll found that 26 per cent of senior school leaders always advised their gifted pupils to apply to Oxbridge, compared with 14 per cent of classroom teachers. And more than a third of the leaders - 36 per cent - said that they usually did, compared with 26 per cent of classroom teachers.
But Sir Peter said it was also up to universities to do everything they could to ensure they were accessible to bright pupils of all backgrounds. "That means investing in proven outreach schemes, offering adequate financial support and ensuring that their admissions processes are fair and do not discourage talented state school students," he said.
"It is only by tackling the issue from both the school and university perspectives that we can hope to change things."
Dr Bousted said part of the problem was mixed messages being sent out by elite universities that did not admit a representative number of state school pupils.
"It would be preferable if teachers did feel more comfortable about recommending Oxbridge," she said. "But we have to ask questions about why they don't and I don't think it is because they are unambitious for their pupils." She pointed out that the two universities did not provide a complete range of courses.
A University of Oxford spokeswoman said: "These findings are incredibly frustrating, not only because state students are in the majority at Oxford - 58 per cent - but because of all the outreach work we do in state schools, running over 1,500 events a year and spending millions on activities.
"Sadly, just one bad headline can unravel that work in an instant. So you can't blame the teachers - media coverage of Oxbridge is weighted towards the negative and stereotyped."
A spokesman from the University of Cambridge said: "The University of Cambridge recognises that teachers are key allies in encouraging the most able students to consider applying to top universities like Cambridge, and works across the whole of the UK to engage with them, offer advice and support, and challenge the outdated myths about Cambridge, which can deter bright students from applying."
Dr Bousted said: "Teachers know their pupils and they care for them and they want to make recommendations that will help them succeed. The vast majority of working-class pupils might well be wanting somewhere closer to home where family support is close at hand, where you won't get into a lot of debt and where there will be people like you."
How frequently do you advise academically gifted pupils to apply to Oxbridge?
Always - 16%
Usually - 28%
Rarely - 29%
Never - 19%
Don't know - 10%.