Two New Zealanders own as much wealth as the nation's poorest 30 per cent, a new global report has revealed.

The nation's richest man Graeme Hart has an estimated wealth of $9 billion, while Singapore-based Richard Chandler holds about $3.8 billion, giving them a combined wealth that Oxfam says is the same as the bottom 30 per cent.

Globally, eight men own the same wealth as the 3.6 billion people who make up the poorest half of humanity.

Oxfam said big businesses are avoiding taxes, driving down wages and using their power to influence politics, which is fuelling inequality.

The same research found the richest one per cent own 20 per cent of New Zealand's wealth while 90 per cent own less than half.

Oxfam New Zealand executive director Rachel Le Mesurier said the government needs to tackle inequality.

"By cracking down on tax avoidance wherever it is, and using that money to make our country,and the global economy, a fairer place," she said.

"We were shocked to discover the level of wealth inequality in our country. The gap between the extremely wealthy and the rest of us is greater than we thought, both in New Zealand and around the world. It is trapping huge numbers of people in poverty and fracturing our societies."

The Salvation Army has called for 2017 to be a year New Zealanders take care of their most vulnerable citizens.

It's director of social policy and parliamentary unit, Lieut-Colonel Ian Hutson, said "inequality of this type is not socially or economically healthy for New Zealand".

"Addressing our wealth gap will be a step in the journey towards a more inclusive and socially just New Zealand."

Labour leader Andrew Little said improving wages and restoring home ownership are fundamental to improving inequality.

"New Zealand has always been about ensuring everyone has a fair shot and a fair share," he said.

"Rather than building their wealth, young families are stuck paying someone else's mortgage."