The second most represented group was Vietnamese followed by Korean. In total, 3912 students were awarded a selective school place last year, with 5516 applicants from a non-English speaking background - 42 per cent (1828) of whom were successful.

The dominant cultural group is Chinese, with the most applicants and the highest success rate in the entry test. Last year, 2361 applicants were from a Chinese background and 1242 were successful.

On average only 20 per cent (or 320 students each year) are from an English-speaking background.

Children of migrants fill almost 80 per cent of the places offered at the state's top 10 selective high schools, which are all ranked in the top 20 HSC performers.

Only 41 students from an English-speaking background are studying at the school - an average of seven in each year.

The co-director of the Centre for Population and Urban Research at Monash University, Bob Birrell, said the successful students largely represented middle- to upper-middle-class families from Asia who put a heavy emphasis on education and professional achievement.

He said selective schools were not providing assistance to the vast majority of families. ''In NSW we are entrenching advantage within one particular ethnic group. If the NSW government was serious about equal opportunity, it would put some geographical boundaries to ensure better access to [top] schools.''

A specialist in schools systems from the University of Melbourne, Richard Teese, said that the pooling of high achievers in selective and private school systems had raised the performance bar beyond the reach of students in mainstream schools.

''When you pool resources like that you multiply their impact and you give the students who have access to that distinctive advantages over everybody else,'' Professor Teese said.

''You are setting up a situation in which you [create] extremes of advantage and extremes of disadvantage. If you took those students out of those hot-house environments they would still do well. But by combining their resources you multiply their advantage. It is a zero-sum game: some win, but others must lose.''