A child poverty report which has ranked New Zealand in the bottom half of developed nations has sparked calls for better monitoring, which one groups says has reached crisis point.
The Unicef report, Measuring Child Poverty, ranked New Zealand 20th out of 35 OECD economies for child poverty.
It used the number of households earning less than 50 per cent of the median income as a measure.
The report also ranked 29 developed countries on deprivation - a measure which looks at the likes of services, opportunities and possessions rather than income alone. New Zealand was not included in deprivation rankings because the data was not up to date.
Every Child Counts, a coalition of child advocacy groups, said the report revealed a crisis in monitoring of child poverty.
Unicef New Zealand executive director Dennis McKinlay said it was imperative to have more immediate data to measure deprivation in New Zealand.
"We need to know how we compare in the international setting so that we can find ways to do better for children who are missing out on some of their basic rights."
Ministry of Social Development data puts New Zealand's deprivation rate at 18 per cent, compared with 15 per cent in Britain, which New Zealand ranked ahead of on the income-based poverty measure.
"The report showed spending on children and families in New Zealand was relatively high, at 3 per cent of GDP.
But Mr McKinlay said much of that went towards remedial services to counter low spending in early childhood, which was less than half the OECD average.
The report also found poverty was not an inevitable situation but was susceptible to government policies.
The report said the full impact of the global recession was yet to be measured, but children were disproportionately affected.
Mr McKinlay said the failure to protect children from today's economic crisis was one of the most costly mistakes a society could make.
Every Child Counts manager Deborah Morris-Travers said children in the early years of life were the most vulnerable to the negative impacts of poverty.
"This highlights the need to closely monitor poverty and deprivation and set time-specific targets to improve the living standards of these children."
Ririki executive director Anton Blank said Maori and Pacific children bore the brunt of child poverty.
A "massive brown underclass" was developing as their populations grew, which would have serious social and economic consequences, he said.
"This is a Polynesian time bomb."
Mr Blank said the report reinforced that child poverty could be alleviated by good policy choices.