UN calls for billionaires tax to help poor

A tax on billionaires is among the options in a UN report to help raise more aid for the poor. (AAP)

A tax on billionaires is among the options in a UN report to help raise more aid for the poor. (AAP)

A tax on billionaires and a $25 a tonne carbon tax are among the options in a UN report to help raise more aid for the world's poor.

The United Nations has called for a tax on billionaires to help raise more than $US400 billion ($A390 billion) a year for poor countries.

A $US25-a-tonne carbon tax is another measure proposed in a new report, which accuses wealthy nations of breaking promises to step up aid for the less fortunate.

The UN's annual World Economic and Social Survey also says it is critical to find new ways to help the world's poor as pledged cash fails to flow.

The report estimates that the number of people around the globe worth at least $US1 billion rose to 1226 in 2012.

These include an estimated 425 billionaires in the United States, 315 in the Asia-Pacific region, 310 in Europe, 90 in other North and South American countries and 86 in Africa and the Middle East.

Together they own an estimated $US4.6 trillion or $US3.75 billion per person.

The UN estimates a one per cent tax on their wealth would raise $US46 billion in 2012.

"The 'average' billionaire would own $US3.7 billion after paying the tax. If that billionaire spent $US1000 per day, it would take him or her over 10,000 years to spend all his or her wealth," the report says.

Other ideas for international taxes include:

- A tax of $US25 per tonne on carbon dioxide emissions would raise about $US250 billion. It could be collected by national governments, but allocated to international co-operation.

- A tax of 0.005 per cent on all currency transactions in the dollar, yen, euro and pound sterling could raise $US40 billion a year.

- Taking a portion of a proposed European Union tax on financial transactions for international co-operation. The tax is expected to raise more than $US70 billion a year.

It also suggests expanding a levy on air tickets that a number of nations already impose to raise money for drugs for poor states through UNITAID, a UN initiative.

The report says more than $US1 billion has been handed over to UNITAID since the levy started in 2006.

Budget cuts have meant aid and development assistance to poor countries fell $US167 billion short of promised levels in 2011, Rob Vos, the report's lead author, said.

"We are suggesting various ways to tap resources through international mechanisms such as co-ordinated taxes on carbon emissions, air traffic and financial and currency transactions."