Peter Reynolds, chief executive of the Early Childhood Council, said it was hard to compare countries because the systems were often structured differently.

He said most early childhood education in New Zealand was professionalised, with qualified teachers.

 "This significantly increases cost if compared to more care-oriented models. The New Zealand model also operates from age zero to five inclusive, where many overseas models operate a more age-restrictive model."

Reynolds said it was correct that New Zealand was "relatively expensive" by international standards.

"But for that investment, we get what we seek – a highly professional early childhood education (ECE) system, focussed on education and development. Of course, the system in New Zealand, while widely regarded as one of the best in the world, is not perfect. Research shows for every dollar invested in ECE, an $11 return over time is achieved. That timescale, about 20 years, is far longer than most politicians will tolerate. The return comes from reductions in state support - health, housing, welfare, justice - and a stronger return to the economy through a more highly-skilled workforce."

He said it was hard to demonstrate the level the system was operating at.

"To close that loop, we need to get more outcome-focussed and reduce the reliance on inputs and compliance."

​Rrahul Dosshi, managing director of The Rainbow Corner, which also operates Porse, said the cost of teaching staff had increased 27 per cent in the past two or three years.

Some operators had to pass some of that back to families, he said. 

Education Minister Chris Hipkins said the Government was already doing its bit.

"The Government subsidises all children aged zero to five attending early childhood education services for up to 30 hours per week. Children over three attract a higher level of funding for 20 hours a week.  The Government pays the funding to services, most of whom also charge fees or seek other contributions from parents. While services are regulated and funded by government, they are independent entities which make their own operational decisions. Funding is demand driven, so if more children enter ECE, the total amount government spends on ECE also increases."

He said funding had increased 1.6 per cent at the beginning of 2019 and, next January about 4200 centres would get another 1.8 per cent increase in their subsidy rates.

"The current appropriation for early childhood education exceeds $1.8 billion."