The fortunes of the world's 2,208 billionaires grew by $US2.5 billion a day last year while the 3.8 billion people who make up the poorest half of humanity saw their wealth decline by 11 per cent.

The figures - which also show some 3.4 billion people are now living on less than $US5.50 a day - are among the findings of the latest Oxfam briefing paper on inequality in the world, Public Good or Private Wealth?.

Public Good or Private Wealth

Released ahead of this week's gathering of world political and business leaders for the World Economic Forum in Davos, Switzerland, the report found that over the past year, wealth has become even more concentrated with 26 people owning as much wealth as the world's poorest 3.8 billion, down from 43 people the year before.

Jeff Bezos, the owner of Amazon, saw his fortune rise to $US112 billion - just one per cent of which is equivalent to the whole health budget for Ethiopia, a nation with a population of 105 million people, it said. 

The report said the human costs of inequality - which sees 263 million children not allowed to go to school and 10,000 people dying every day because they cannot access healthcare - is "devastating" and calls for economies to be transformed to "deliver universal health, education and other public services".

"To make this possible, the richest people and corporations should pay their fair share of tax," it said. "This will drive a dramatic reduction in the gap between rich and poor and between women and men."

The report said getting the richest one per cent to pay just 0.5 per cent extra tax on their wealth would raise more money than the cost of educating the 262 million children who can't go to school or more than the cost of healthcare saving the lives of 3.3 million people. Noting that tax rates for wealthy individuals and corporations has been cut dramatically in recent years, the report calls for wealth and capital to be taxed at "fairer levels". 

Winnie Byanyima, executive director of Oxfam International, said the size of a person's bank account "should not dictate how many years your children spend in school, or how long you live – yet this is the reality in too many countries across the globe".

"While corporations and the super-rich enjoy low tax bills, millions of girls are denied a decent education and women are dying for lack of maternity care.”

In Australia, 43 billionaires - up from 33 the year before - took in a collective $100 million a day last year with the top one per cent of Australians owning more wealth than the bottom 70 per cent combined.

Dr Helen Szoke, Oxfam Australia's chief executive, said the paper showed the most disadvantaged in the country - including many Indigenous people - remained trapped in an entrenched cycle of poverty. She also highlighted the "economic disadvantage" women continue to face.

“The government should introduce tougher tax laws that require large Australian companies – a third of which paid zero into the public coffers over four consecutive years – to publicly report on their tax affairs by country...” Dr Szoke said.

“Australia is among the wealthiest nations in the world, yet the pervasive gap between the haves and the have-nots persists. This inequality simply cannot – and does not need to – continue.”