Zimbabwean President Robert Mugabe defended land policies blamed for devastating his country's agricultural sector, asserting at a U.N. food summit Tuesday that the West was trying to cripple the nation's economy.

Mugabe's presence at a summit addressing high global food prices sparked protests from some world leaders. He is blamed for the economic collapse of a country once considered a regional breadbasket and Zimbabweans increasingly are unable to afford food and other essentials.

Zimbabwe is not subject to broad sanctions affecting ordinary citizens. Western sanctions are targeted instead at the president and several dozen close associates.

Mugabe nonetheless contended that his policies of redistributing land taken from large farmholders were "warmly welcomed by the vast majority of our people" and the sanctions aim to "cripple Zimbabwe's economy and thereby effect illegal regime change in our country."

"The United Kingdom has mobilized her friends and allies in Europe, North America, Australia and New Zealand to impose illegal economic sanctions against Zimbabwe," he said.

U.S. State Department spokesman Tom Casey criticized Mugabe's attendance at the summit, saying his "misrule" serves as "an example of what not to do in terms of managing agricultural and food policy."

Australia's foreign minister decried Mugabe's participation as "obscene". The Dutch ministry for overseas development pledged to ignore the ruler.

The Rome-based U.N. Food and Agriculture Organization is hosting the three-day summit to try to solve the short-term emergency of hunger caused by soaring prices, and to help poor countries grow enough food to feed their own.

U.N. Secretary-General Ban Ki-moon told world leaders that global food production must rise by 50 percent by 2030 to meet increasing demand.

Ban said that nations must minimize export restrictions and import tariffs during the food price crisis and quickly resolve world trade talks.

"The world needs to produce more food," Ban said.

In a message read to the delegates, Pope Benedict XVI said "hunger and malnutrition are unacceptable in a world which, in reality, has sufficient production levels, the resources, and the know-how to put an end to these tragedies and their consequences."

The United Nations is encouraging summit participants to start undoing a decades-long legacy of agricultural and trade policies that many blame for the failure of small farmers in poor countries to feed their own people.

Wealthy nations' subsidizing their own farmers makes it harder for small farmers in poor countries to compete in global markets, critics of such subsidies say. Jim Butler, the FAO's deputy director-general, said in an interview ahead of the gathering that a draft document that could be the basis for a final summit declaration doesn't promise to overhaul subsidy policy.

"Some countries have taken action by limiting exports or by imposing price controls," Ban said. "They only distort markets and force prices even higher."

The increasing diversion of food and animal feed to produce biofuel, and sharply higher fuel costs have also helped to shoot prices upward, experts say.

President Mahmoud Ahmadinejad, whose presence at the summit also came under protest, denounced wealthy Western nations for subsidizing their own farmers. He asked: "Why do some powers turn the food of the people into an object for profiteering?"

Some protesters climbed up the lower tier of the Colosseum and sent down leaflets criticizing the Iranian leader, who repeated calls for the disappearance of Israel.

Congress last month passed a five-year farm bill heavy on subsidies, bucking White House objections that such aid in the middle of a global food crisis wasn't warranted.

While leaders met in Rome, EU finance ministers discussed a report on the food crisis in Luxembourg. The European Commission's report urged the bloc to rally international support to end export restrictions on food, offer aid to poor nations and promote the "sustainable" use of biofuels.

The head of the Rome summit's U.S. delegation, Agriculture Secretary Ed Schafer, insisted on Monday that biofuels will contribute only 2 or 3 percent to a predicted 43 percent rise in prices this year.

Figures by other international organizations, including the International Monetary Fund, show that the increased demand for biofuels is contributing by 15-30 percent to food price increases, said Frederic Mousseau, a policy adviser at Oxfam, a British aid group.

"Food stocks are at their lowest in 25 years, so the market is very vulnerable to any policy changes," such as U.S. or European Union subsidizing biofuels or mandating greater use of this energy source, Mousseau said.

Brazil is another large exporter of biofuels, and President Luiz Ignacio Lula da Silva defended the alternative fuels.

"It offends me to see fingers pointed against clean energy from biofuels, fingers soiled with oil and coal," said Silva, whose country's sugar cane has long been used to produce ethanol. He insisted that biofuels "are not the villain menacing food security in poor countries."

Silva alluded to wealthy nations' farm subsidiaries as a key culprit for food insecurity.