Associate Education Minister John Banks has defended his support for non-registered teachers working in charter schools in the wake of criticism from political opponents and unions.
Last month Mr Banks and Education Minister Hekia Parata announced that charter schools would be able to negotiate a percentage of unregistered teachers.
That came despite a Ministry of Education recommendation that all teacher be registered to give students the greatest learning opportunities.
The recommendation, written before the decision and released last week, warned there was a high potential for a negative impact on students' education from teachers who did not meet minimum standards.
"Teacher registration is one the most influential levers in raising teacher quality across the profession in both state and private schools," the ministry said. "Allowing charter schools to stand outside this work will significantly damage the credibility of the Crown.''