Les Ebdon, appointed as director of fair access by UK's coalition government last year, warned that Asian parents were putting excessive pressure on their children, who then find they are not suited to the course.
The former vice-chancellor Bedfordshire told 'The Sunday Times' that some find the pressure so intense that they drop out or even break down.
"One of the underlying reasons for the under- representation of ethnic minorities in some highly selective universities is because they apply predominantly for medicine and law, both highly competitive courses, and a significant amount of that is parental pressure," said Ebdon, who has been pushing for top UK universities such as Cambridge and Oxford to be more socially mixed and less dominated by the middle classes.
"Deans of medical schools tell me some students face this terrible dilemma of a strong push from their parents but actually they decide that medicine is not for them," he added.
Many ambitious and upwardly mobile families from minority groups based in the UK encourage their children to pick law or medicine as both have long been seen as an assured route to a respected and secure career.
A study published last year by the British Medical Journal found that a third of medical students are from ethnic minorities, a majority of whom are of Indian-origin.