Hundreds of economists including scholars from Oxford University and the University of California, Berkeley, are asking the Group of 20 nations to impose limits on speculative positions in food commodities to curb volatility in crop prices.

“With around 1 billion people enduring chronic hunger worldwide, action is urgently needed to curb excessive speculation and its effects on global food prices,” according to a letter signed by 461 economists and sent to finance ministers from the G-20, which includes the world’s richest nations. The letter, dated Monday, was posted on Oxfam America’s website.

Research sponsored by the United Nations, International Monetary Fund and other global organizations suggest speculation in crop futures by index funds and large banks may cause price spikes that can put grocery costs out of reach for poorer people. Global regulation of speculators has been a goal of French President Nicolas Sarkozy during his term as leader of the G-20 this year.

EU finance ministers last week agreed to a derivatives- regulation plan that may require exchanges and other venues to share trading data with rival clearinghouses to make futures speculation more transparent. In the U.S., some rules on commodities trades under a financial-reform law passed in 2010 won’t be completed until at least the first quarter of 2012, Commodity Futures Trading Commission Chairman Gary Gensler said last week. A CFTC vote on position limits, one of the bill’s most contentious components, could happen as soon as Oct. 18.

Facing Choices

“There is a choice that the CFTC and the EU have to make,” Rohit Malpani, an adviser to Oxfam America, the U.S. arm of Oxford, U.K.-based Oxfam International, one of several groups that helped organize the letter, said last week in a telephone interview. “Listen to experts or those impacted by high food prices, or listen to those who are benefiting from volatility, largely the banks and funds that have increasingly moved to these markets.”

The CFTC’s proposals on position limits and derivative exchanges “often represent an overstepping of the commission’s authority” under Dodd-Frank, Terrence Duffy, the executive chairman of CME, the world’s largest futures trader, said in testimony submitted to the Senate Banking Committee in April. Numerous published studies question any connection between speculation and price volatility.

The economists’ letter was also sent to all CFTC members and to Michel Barnier, the European Union’s financial-services commissioner.

Global food prices have increased 16 percent in the past year, the UN says. The world’s population is forecast to jump to 9.3 billion by 2050 from an estimated 6.9 billion in 2010, requiring a 70 percent increase in food production, according to the agency. In February, when costs peaked, the World Bank said the increased expense had pushed 44 million people into “extreme poverty” in a little over half a year.