A growing population also contributed to greater demand for food. According to Josette Sheeran, director of the WFP, "There are 854 million hungry people in the world and 4 million more join their ranks every year."

"We are facing the tightest food supplies in recent history. For the world's most vulnerable, food is simply being priced out of their reach," he said.

According to Japan's Economist magazine, after the U.S. subprime mortgage crisis triggered a turmoil on the international financial market, a huge amount of speculative funds has flowed into the less risky agricultural commodities futures market, pushing food price up along with oil, gold and other commodities.

High oil prices and the promotion of biofuels in many developed countries have further stimulated the surge of food price. The expensive oil has raised the cost of farm production in its various phases, such as crop growth and product transportation. Biofuels directly consume crops such as maize. Some developed countries have encouraged the use and production of biofuels in recent years in a bid to reduce greenhouse gas emission and dependence on oil imports. The direct negative side effect is the reduction of staple food for human consumption, subsequently pushing the price up.

Consequences

Skyrocketing prices on rice, wheat, corn and other staple foods like milk have direct impact on ordinary people's lives, particularly those in Africa, where the bulk of income is spent on the bare necessities for survival. Soaring food prices have incited unrest in some hard-stricken countries, such as Haiti, Egypt and the Philippines. According to the FAO, 37 countries currently face food crises.

The continuing rice riots in Haiti recently have forced Prime Minister Jacques Edouard Alexis to step down. In Asia, the soaring prices of rice, a staple food in the region, is putting leaders under intense pressure as mounting strikes and protests are demanding pay hikes to keep up with the rising costs of living.

On Saturday, about 20,000 workers rioted over high food prices and low wages on Saturday close to the Bangladeshi capital Dhaka amid spreading global unrest over soaring food costs.

In Sierra Leone, one of Africa's poorest nations, rice price has soared 300 percent. Rice prices in Cote D'ivoire, Senagal and Cameroon also jumped 50 percent. Western African countries such as Cote D'ivoire, Mauritania, Senegal and Burkina Faso have all witnessed protests against soaring food prices over the past few days.