The State Government is seeking legal advice on whether religious schools should be stripped of the right to discriminate against teachers and students on the basis of their sexuality amid concerns that they may refuse to enrol children from same-sex families.

With expectations growing that the same-sex marriage survey will return a Yes vote next week, advocates for WA’s gay community are calling for an “anti-gay loophole” in the State’s Equality Opportunity Act to be closed to prevent private schools from sacking gay teachers or expelling LGBTI students.

In a letter to Premier Mark McGowan obtained by The West Australian, the advocates argue that WA’s special exemptions for religious schools are the broadest in the nation and are being used to target members of the LGBTI community.

“In other mainland States, exemptions for religious schools are often defined only to apply to staff members whose job has a specific religious purpose,” Same-Sex Parents Association spokeswoman Maxine Drake said. “WA’s extraordinary loophole for church schools is so wide and poorly written, it even allows students to be expelled if they have gay parents.”

The letter points to a 2015 example in which a seven-year-old girl was withdrawn from Mandurah’s Foundation Christian College after her gay father was reportedly told that she could only stay on as a student if she never discussed his sexuality.

“The principal of the school was noted as saying at that time, ‘If I’d known she had gay dads, I would never have enrolled her’,” the letter says.

The letter is also signed by veteran gay rights advocate and former Australian Democrats senator Brian Greig, who believes community attitudes have shifted dramatically.

He said staff at religious schools in WA would be “especially vulnerable” after marriage equality was achieved nationally, with teachers who wished to legally marry under Federal law able to be legally sacked under State law.

A spokeswoman for Attorney-General John Quigley said the Government was seeking legal advice and it would be considered by Cabinet “in due course”. She said the Government, which last week introduced laws to expunge outdated convictions against LGBTI people, would continue to address discrimination against WA’s LGBTI community.