But groups representing many private and religious schools warn that if a bill to change the law is successful, it could threaten their religious freedom and leave them open to litigation for operating the schools in accordance with their faith.

Sydney MP Alex Greenwich has put a private member's bill before the NSW Parliament to amend the Anti-Discrimination Act and remove the exemption for private schools prohibiting the expulsion of students because they are gay.

Sixty-six per cent of respondents to an automated phone poll commissioned by Mr Greenwich and conducted by Reachtel last week said they did not support the present laws, while 18 per cent did support them and 16 per cent were undecided. Of the 1200 people surveyed, 72 per cent did not know private schools were allowed to discriminate against students on the basis of sexuality, marriage status and disability.