"The global food crisis is a wake-up call for Africa to launch itself into a 'green revolution' which has been over-delayed," Nigerian Agriculture Minister Sayyadi Abba Ruma said on the second day of the three-day summit.

"Every second, a child dies of hunger," the minister said. "The time to act is now. Enough rhetoric and more action."

U.N. Secretary-General Ban Ki-moon received a petition signed by more than 300,000 people saying there was no time to lose. A draft declaration from 151 countries taking part said: "We commit to eliminating hunger and to securing food for all."

The U.N. Food and Agriculture Organisation called the summit after soaring commodity prices threatened to add 100 million more people to the 850 million already going hungry and caused food riots that threaten government stability in some countries.

The cost of major food commodities has doubled over the last couple of years, with rice, corn and wheat at record highs. The OECD sees prices retreating from their peaks but still up to 50 percent higher in the coming decade.

Ban said the summit was already a success. "There is a clear sense of resolve, shared responsibility and political commitment among member states to making the right policy choices and investing in agriculture in the years to come.

"Hunger degrades everything we have been fighting for in recent years and decades," he told reporters. "We are duty-bound to act to act now and to act as one."

Ban's predecessor at the head of the United Nations, Kofi Annan, was in Rome to sign an agreement with U.N. food agencies for a new drive to increase farm production in Africa.

BREADBASKET

"We hope to spur a green revolution in Africa which respects biodiversity and the continent's distinct regions," said Annan, who chairs the Alliance for a Green Revolution in Africa (AGRA) which is coordinating the effort.

The scheme will provide technical support to improve soil and water management, access to seeds and fertilisers, and improve infrastructure in "breadbasket" areas of Africa which have relatively good conditions for farming.

The Nigerian minister said his country had "the potential to become the food basket of Africa". But its farms were 90 percent dependant on rainfall, making them vulnerable to climate change, and its 14 million smallholders used "rudimentary" techniques.

The Rome summit will set the tone on food aid and subsidies for the Group of Eight summit in Japan in July and what is hoped to be the concluding stages of the stalled Doha talks under the World Trade Organisation aimed at reducing trade distortions.

As leaders made lofty speeches, many blaming trade barriers and biofuels for driving up prices, delegations worked on a summit declaration for release on Thursday.

A draft of the declaration promised to "stimulate food production and to increase investment in agriculture, to address obstacles to food access and to use the planet's resources sustainability for present and future generations".

The United States found itself on the defensive regarding biofuels, along with Brazil which is the world's largest producer of sugar-cane ethanol, and U.S. Agriculture Secretary Ed Schafer bristled at the criticism.

"I don't think the United States gets enough credit at all for providing over one half of all the food aid," he said.

Zimbabwe's Robert Mugabe, who told the summit on Tuesday that former colonial power Britain was to blame for many of his country's problems, came under fire from a human rights group which said he was using food as a weapon ahead of a June 27 presidential run-off election.

Human Rights Watch said the Harare government was deliberately stopping food aid being provided to supporters of opposition leader Morgan Tsvangirai.

"President Mugabe's government has a long history of using food to control the election outcome," it said.