NSW school children are facing unprecedented hurdles to get into ethics classes in schools, the state's provider of ethics classes has warned.

For the first time this year parents of kindergarten students do not have to be informed of the availability of ethics classes by the school principals until after they have been through at least four different steps.

"It's blatant discrimination based on religious grounds," said the chairman of Primary Ethics, Bruce Hogan.

New department guidelines say parents who leave their child's religious persuasion blank on the enrolment form should first be sent a letter by the principal advising them of all the religious education options available at the school. If parents choose not to select a religious denomination, their child will then be engaged in "meaningful activities" such as sitting in the library. Only then will they be informed of the availability of ethics classes and formally able to enroll.