Integrated schools are taking the government to court over its refusal to give them millions of dollars of extra property funding.
The Association of Proprietors of Integrated Schools said the government should have included them when it announced at the end of last year it was giving state schools $400 million to spend on their buildings as part of a wider package of infrastructure spending.
The association's spokesperson and former chief executive Paul Ferris told RNZ it had been negotiating with the government for a share of the money for most of the year, but was told in September it could not afford to extend the payment to integrated schools.
He said the organisation this week filed papers in the High Court in Wellington seeking a judicial review of the government's decision.
Ferris said integrated schools were part of the state network and the government was obliged to maintain the schools' property to the same standard as other state schools.
The payments were worth between $50,000 and $400,000 per school and Ferris said extending the money to integrated schools would cost about $50 million.
He said the government was expected to respond by 8 December.
"This is not a matter of discretion, this is a legal entitlement that we have under the agreements we have with the government on integration," he said.
"In the Catholic space, we give the government the use of $2.6 billion dollars worth of property to use rent-free every year and the government agree to maintain it to a similar standard to a similar state school and if they spend it on a state school, they should be spending it on a state integrated school."
Education Minister Chris Hipkins said he could not discuss a matter that was before the court or the government's legal strategy.
"State-integrated school representatives, however, have contacted the government and I look forward to discussing this topic, and others, with them early in the New Year. I remain hopeful we can find a satisfactory solution," he said.
Hipkins said the Education Ministry's negotiations with integrated schools began before the severity of Covid-19 was fully known.
"I remain supportive, in principle, of finding a solution in this area, however our challenge is being able to fund a solution given the impact of Covid-19 on our country," he said.
"The government has decided to set aside the remainder of the Covid Response and Recovery Fund in the event, for example, that New Zealand experiences a further wave of Covid-19. Therefore, any initiative to accelerate upgrades of the state-integrated school portfolio will now need to be considered as part of decision-making for Budget 2021."
Integrated schools are privately owned, many of them by the Catholic or Anglican churches, but the government pays their running costs on the same basis as state schools.
The schools charge compulsory attendance dues to cover the cost of insurance and loans used in the construction of their buildings.
Some have been criticised for requesting relatively high donations and for charging high fees for boarding and lunches.