Teachers' union NZEI is frustrated more money is being poured into a new round of charter schools.

President Louise Green said there are lots of issues in the public system which need addressing, and require money, yet public schools are effectively facing cuts in their operational funding.

"While money is being siphoned off, wasted on this experiment that hasn't been proven and certainly not evaluated, the majority of our kids in public schools are missing out."

Green said so much charter school cash has been salted away by the operating trusts, misused or spent on high salaries for executives.

"We know at the same time there are schools all around the country asking for more money to support children with learning needs and behavioural needs and that those needs aren't getting addressed."

She said charter schools are an "experiment that hasn't been proven".