Rising food costs threaten to unleash a "silent tsunami" of hunger around the world, the head of the United Nations World Food Programme said Tuesday at a summit in Britain to discuss the crisis.

The head of the agency's World Food Programme, Josette Sheeran, said spiralling food prices could push more than 100 million people worldwide into a level of poverty where they cannot afford to feed themselves.

"This is the new face of hunger — the millions of people who were not in the urgent hunger category six months ago but now are," said Sheeran.

The summit, hosted by British Prime Minister Gordon Brown, is aimed at figuring out a plan to address the food crisis to present to the European Union, the G8 and a special UN meeting over the next few months.

Among those attending the meeting are UN officials, policymakers and experts.

Protests and riots have broken out in several developing countries in response to the rising costs of staples such as corn, wheat and rice. The rising prices are due to a combination of poor harvests, rising energy prices, growing demand in India and China, and the increasing use of fields to produce corn for ethanol.

Sheeran said the crisis is "a silent tsunami that respects no borders."

"The world's misery index is rising … as soaring food and fuel prices roll through the lives of the most vulnerable," she said Friday.

$755 million needed

The WFP says the food crisis is the biggest challenge it has faced in its 45-year history and it is forcing the agency to look at cutting aid to some recipients.

A program to feed 450,000 children in Cambodian schools may have to be cut beginning in May unless new funding can be found, the WFP says.

Sheeran said that $12 billion in donations poured in following the devastating tsunami in 2004 that left nearly a quarter of a million people dead in Southeast Asia. "We need that same kind of action and generosity [again]," she said.

On the weekend, UN Secretary-General Ban Ki-moon said the WFP needs an extra $755 million to cover the rising costs of existing emergency operations.

"Tackling hunger is a moral challenge to each of us and it is also a threat to the political and economic stability of nations," Brown said in an article on the government website.

"So I believe we need to see a fully co-ordinated response by the international community."

He signalled that Britain may be willing to rethink its stance on biofuel targets if it might reduce the impact on food prices.

"If our U.K. review shows that we need to change our approach, we will also push for change in EU [European Union] biofuels targets," he wrote.

Unrest over the food crisis has led to deaths in Cameroon and Haiti, cost Haitian Prime Minister Jacques Edouard Alexis his job, and caused hungry textile workers to clash with police in Bangladesh.

Former UN secretary-general Kofi Annan said more protests in other developing nations appear likely. "We are going through a very serious crisis and we are going to see lots of food strikes and  demonstrations," Annan told reporters in Geneva.

With files from the Associated Press