The union representing ACT teachers has called for government funding to be cut from Canberra Grammar School after it received a $20 million donation.
The donation, one of the largest endowments made to a school, was given by Canberra Airport executive chairman and Canberra Grammar old boy Terry Snow.
In a motion made at a meeting of the Australian Education Union's ACT branch council, members voted to call for funding from the federal and territory governments to be recalled from the private school.
The donation will fund a 1400 seat music auditorium, along with a new library and learning centre, opening in 2021.
It's estimated Canberra Grammar receives $7 million a year in government funding, along with a further $34 million from parent fees.
Union secretary Glenn Fowler said the larger issue of inequality in school funding needed to be addressed.
"When did some children become more important than others?" Mr Fowler asked.
"The fact that our private schools are overfunded and our public schools are underfunded is a source of national shame, and this latest effort is the final kick in the teeth.
"If [Terry Snow] wants to give the money, it's up to him to donate the money to the school, but it should have an effect on government funding."
In a statement, the education union said the large donation should mean a rollback of funding from governments to the school.
"Council remains outraged that Australia's school education system is one of the most segregated in the world and that the funding of Australian schools is becoming increasingly inequitable," the union said.
Mr Snow said earlier this month his former school was a Canberra institution and wanted to keep its heritage alive.
"Anything I'm associated with, I try and commit to doing as good a job as I possibly can, and I would like to see this school be the high-water mark for independent education in Australia," he said.
The Canberra Airport owner is one of the wealthiest people in the country, with a reported fortune of $1.8 billion.
The education union has also called for future government funding to the school to be repurposed to support the education of disadvantaged students, along with music education.
Mr Fowler said it was unlikely the ACT and federal governments would stop funding to Canberra Grammar School, but called for a funding shift.
"If a school has its own means, it shouldn't be relying on the government to be propped up."
"Our members are frustrated that they're struggling to provide basic resources for students."
A spokeswoman for ACT Education Minister Yvette Berry said the model for funding independent schools was set to change.
"The government is transitioning that funding to be consistent with the schooling resource standard," the spokeswoman said.
"In the 2019-20 budget, the government increased funding for public schools by 7 per cent and decreased funding for non-government schools by 1 per cent.
"ACT public schools are among the best resourced in the country and has the highest paid public school teachers in the country."
Mr Snow has donated more than $26 million to various causes through his foundation over the past 28 years.
Canberra Grammar has not said how much of the endowment from Mr Snow would be earmarked for Indigenous and equity scholarships.
The ACT government has also flagged plans to roll out needs-based funding in line with the Commonwealth, beginning with resources for students with a disability in 2020, but has not released further detail.
When asked last month if ACT public schools had ever received large donations, an education directorate spokesman said all schools were funded by the government.
- with Sherryn Groch