New Zealand's persistent high rate of child poverty has been highlighted in Amnesty International's latest look at the state of human rights around the world.

"Nearly one in three New Zealand children live below the poverty line," the group's 2016/2017 report reads.

Paediatrician Innes Asher, former head of the University of Auckland's paediatrics department, says the Government has done nothing to fix it - despite former Prime Minister John Key's promises.

"Key said after the last election reducing rates of poverty and hardship were his priority for this term - we haven't seen any significant changes," Dr Asher told The AM Show on Thursday.

"We have, every year in New Zealand, about 40,000 children... admitted to hospital for diseases that are potentially preventable by solving poverty, housing and great access to healthcare. There's a lot we could do."

The 2015 Budget gave low-income families about $25 extra a week, touted by the Government as the biggest increase in 30 years.

But Dr Asher says that amounts to "almost nothing" - and certainly doesn't make up for the $72.50 in tax credits three-child families without parents in paid work are missing out on.

"By not adjusting Working for Families properly... the country's been saving billions of dollars over the last several years," says Dr Asher.

"Families and children have been specifically disadvantaged by the Government's policies."

Reversing the 2010 tax cuts would be a start, she says, since low-income families saw little benefit from those.

And while superannuation - available to Kiwis aged 65 and over, regardless of their wealth - has been pegged to the median income, benefits for low-income families have lagged way behind.

"People on benefits, their incomes are proportionally way, way, way below the average income compared to 20 years ago. We haven't done this to the elderly."

Poverty in youth can have a severe impact throughout a child's life, says Dr Asher.

"I see children whose bodies are harmed now, and some that are harmed forever, with diseases that are completely preventable if we didn't have poverty and if we didn't have unhealthy housing arrangements, and if we had good access to healthcare at all times, basic healthcare."

Oxfam earlier this year released a study showing the gap between New Zealand's rich and poor has never been wider - the two richest people now owning more wealth than 30 percent of the adult population combined.

A third of Kiwis worth more than $50 million didn't even pay the top tax rate.

Mr Key blamed the growing disparity on rising house prices.

More problems

Other problems New Zealand is facing, according to Amnesty International's report, include:

high levels of sexual violence against women and girls

a "significant number of children suffering physical and psychological abuse and neglect"

a lack of progress on improving the Bill of Rights Act

disproportionate numbers of Maori in the criminal justice system

consideration of a formal extradition treaty with China, which practises capital punishment.

Newshub.