Schools should not be discriminating against students on the basis of their sexuality, the federal education minister says.
A no-girlfriend rule at Sydney girls school St Ursula's College's year 12 formal rose to national attention this week after a student's online petition rapidly gathered 4900 signatures.
Jason Clare on Friday urged the Catholic school to rethink the ban and "show a little bit of common sense".
"It's 2023," the federal education minister told Seven's Sunrise program.
"You should be able to take whoever you want to the year 12 farewell.
"I don't think any of us think that we should be discriminating against children at our schools on the basis of their sexuality or anything else."
As federal education minister, Mr Clare is responsible for about 60 per cent of the funding Catholic schools receive each year.
Another 15 per cent comes from state governments and the rest from fees, according to the National Catholic Education Commission.
Deputy opposition leader Sussan Ley and NSW Premier Chris Minns have also called on the school to overturn the ban.
Equality Australia said LGBTQ children and staff faced discrimination at religious schools around the country.
"We know of children who have been expelled, denied leadership positions, told they are going to hell, forced into 'counselling' or advised to live celibate lives," chief executive Anna Brown said.
"This is obviously confronting to many people and out of step with the views of the vast majority of people of faith."
St Ursula's has been contacted for comment.
Sydney Catholic Schools said it would not comment on the matter, which was "being addressed at a school level".
"Our priority is seeing our students through to the end of the HSC and 13 years of school with as little disruption as possible," a spokesman said.