"The rush for land is out of control and some of the world's poorest people are suffering hunger, violence and greater poverty as a result," Oxfam Chief Executive Barbara Stocking said from London.
"The World Bank is in a unique position to help stop land grabs becoming one of the biggest scandals of the century.
"Investment should be good news for developing countries -- not lead to greater poverty, hunger and hardship."
International Land Coalition, which monitors land-related projects, said from 2000-10 some 261 million acres of arable land, much of it in impoverished African states, were acquired by outsiders.
Oxfam calculated in a report released Thursday that's enough to feed nearly 1 billion people in a world where food shortages are growing steadily worse as the global population soars and economies crumble.
Yet, Oxfam says, much of the land that's been taken over is being used by speculators, including U.S. banks, hedge funds and other high-profile institutions, to grow biofuels to sell for hefty profits rather than produce food, either for poor Africans or hungry Arabs.
"No one should believe that these investors are there to feed starving Africans, create jobs or improve food security," said Obang Metho of Solidarity Movement for New Ethiopia, a U.S. campaign group.
British environmental expert John Vidal recently observed that the land rush, "which is still accelerating, has been triggered by the worldwide food shortages which followed the sharp oil price rises in 2008, growing water shortages and the European Union's insistence that 10 percent of all transport fuel must come from plant-based biofuels by 2015."
The World Bank has tripled support for land projects to $6 billion-$8 billion a year over the last decade. No data are available on how much of that is used for land grab acquisitions.
However, Oxfam claims 21 formal complaints have been made by communities harmed by World Bank-supported investments with land rights allegedly violated.
The World Bank's lending arm, the International Finance Corp., said it "does not finance land acquisitions for speculative purposes. We invest in productive agricultural and forestry enterprises that can be land intensive to help provide the food and fiber the world needs."
A 2010 report by the Independent Evaluation Group, the World Bank's official monitoring body, said some 30 percent of bank projects involved involuntary resettlement.
Britain's Guardian newspaper reported that the IEG estimated that "at any one time, more than 1 million people are affected by involuntary resettlement in active World Bank-financed projects."
A study on the land grab issue by the California's Oakland Institute, released in June, observed that Harvard and other major U.S. universities were working through British hedge funds and European speculators to buy or long-lease vast areas of African farmland.
The report, which covered Ethiopia, Tanzania, South Sudan, Sierra Leone, Mali and Mozambique, said that Harvard and other universities with large endowments have invested heavily in land grabs in recent years.
"The scale of the land deals being struck is shocking," said Oakland Institute Executive Director Anuradha Mittal.
"The conversion of African small farms and forests into a natural-asset-based high-return investment strategy can drive up food prices and increase the risks of climate change."
Middle Eastern states, led by Saudi Arabia and the United Arab Emirates plus China, were largely responsible for the initial large-scale land purchases, primarily to grow food for their burgeoning populations that geography prevented from growing for themselves.
But these days, says the Oakland Institute, Western funds are behind most of the big deals.
"Companies have been able to create complex layers of companies and subsidiaries to avert the gaze of weak regulatory authorities," Mittal said.
"Analysis of the contracts reveals that many of the deals will provide few jobs and will force many thousands of people off the land."
Oxfam analysts said speculators involved in several thousand land deals concluded in recent years left land in an area the size of Britain either idle, "for its value to increase," or gave it over to growing biofuels for U.S. or European vehicles.