The Anglican Archbishop of Sydney says he is "deeply sorry" for a letter signed by 34 church schools that argued for the preservation of laws giving them the power to discriminate against gay students and teachers.

Archbishop Glenn Davies joined the country's most senior Anglican - Melbourne Archbishop Philip Freier - in telling Attorney-General Christian Porter there was no need for laws that allow religious schools to expel gay students and sack gay teachers.

Bishop Davies said the reaction to the schools' letter showed it was untenable to express religious freedoms as exemptions to anti-discrimination laws, and he asked federal politicians to urgently replace them with "positive protection".

"The intent was to promote religious freedom for Anglican schools but I realise that it had the unfortunate consequence of affecting many gay students and teachers in our schools, for which I am deeply sorry," he said in a statement.

"There were fears that gay students were going to be expelled or gay teachers sacked. This really saddens me.