U.S. Secretary of State Hillary Clinton is warning that unless something is done to hold down rising global food prices, the consequences will be "grave."

Clinton told those at a meeting of the United Nation's Food and Agriculture Organization that the combination of food shortages and rising prices could cause widespread unrest like that seen in 2007 and 2008.

"We must act now, effectively and cooperatively, to blunt the negative impact of rising food prices and protect people and communities," she said at the FAO's headquarters in Rome.

During the 2008 food crisis, the world's biggest rice producers -- Thailand, Vietnam, and India -- cut rice exports to protect domestic supply, leading to record high prices. Riots in dozens of countries took place as a result.

The United Nations estimates 44 million people have been pushed into poverty since last June because of rising food prices.

Clinton urged countries to share food production information, limit export taxes, and resist the temptation to impose export bans "no matter how attractive they may appear to be."