The British-based charity urged this weekend's summit of the powerful G20 group of major economies to back initiatives by the host, South Africa, to address massive global wealth inequality and the debt undermining developing countries.

Billionaires in the 19 countries that are part of the grouping made $2.2 trillion last year as their combined wealth grew to $15.6 trillion dollars, it said, basing its figures on the Forbes list.

"The annual cost to lift up the 3.8 billion people who currently live below the poverty line is $1.65 trillion," it said in a statement.

Oxfam backed a recommendation that South Africa will present to the November 22-23 summit for the establishment of an international panel to tackle inequality in the same way the UN's IPCC works on the threat from global warming.

"If the South African G20 establishes a new International Panel on Inequality it will be a tremendous step in addressing the inequality emergency," executive director Amitabh Behar said in the statement.

Oxfam also called for the world's wealthy to be "fairly taxed in order to help end poverty and fight the climate breakdown."

It singled out the United States, which is boycotting the Johannesburg meeting, as championing "destructive policies -- from reckless tariffs to regressive tax breaks and cuts to life-saving aid" that increase inequality between the rich and poor.

Calling for action on debt, it said 3.4 billion people live in countries that spend more on interest repayments than on education or health.

The G20 includes 19 countries as well as the European Union and African Union, which together represent 85 percent of global GDP and two-thirds of the world population.

South Africa hopes its summit, the first G20 in Africa, will advance issues facing the continent and developing countries in the "Global South" before the rotating presidency is handed to the United States for 2026.