In a country already desperately poor, Haiti's uprising has impeded shipments of food aid and made even the most basic staples too expensive for many Haitians.

Aid agencies warn of a looming crisis because aid deliveries can't get past numerous roadblocks. Relief workers are trying to arrange security so food can be distributed, a situation further aggravated by fuel shortages that have increased shipping costs and prices for everything from beans to cooking oil.

"There's little we can do until a basic level of security is restored," said Rick Perera, a spokesman for the aid group CARE USA (search). "It's impossible to consider new food shipments to northern Haiti."

The 3-week-old rebellion against President Jean-Bertrand Aristide (search) comes on top of December floods that washed away corn and cassava crops in Haiti, the most impoverished nation in the Americas.

The price of a small bag of rice has jumped from 23 cents to 35 cents in Cap-Haitien since the rebellion began.

Roseline Jacques, a 30-year-old mother of seven, used the small amount she gathered from begging and washing clothes to buy a small bag of rice.

With no money for charcoal to cook the rice, she shared a plate of boiled roots with her children. Their only meal of the day was given to them by a neighbor.

"It was bad before. Now it's worse," Jacques said. "It's getting worse every single day."

On the hardest days, "I go to sleep again without having eaten anything," she said.

Aid workers said the conflict is preventing further aid shipments from arriving in Cap-Haitien. They say rebels who seized the city last Sunday looted 800 tons of food from a U.N. World Food Program warehouse.

Food For The Poor (search), a Deerfield Beach, Fla.-based aid group, said it had 15 shipping containers of food ready for Cap-Haitien, but no shipping companies would go there.

Rebel leader Guy Philippe (search) said he would cooperate with aid groups.

The food shortage is "more than serious," said Food For The Poor spokeswoman Ann Briere. "Supplies are exhausted, and there are no reserves available."

Most of Haiti's 8 million people are jobless or without regular work, and many live on less than $1 day.

"Under normal circumstances, they hardly can buy what they need," said Dr. Daniel Rubens, an Argentine representative of the International Committee of the Red Cross. "They are under chronic stress, and this conflict adds a factor of stress."

Looters pillaged 500 containers of U.S. aid Saturday in the capital, Port-au-Prince.

The violence also jeopardizes Haiti's meager ability to produce its own food. Farmers in northwest Haiti have been blocked from traveling to buy seeds for the planting season that starts in March, according to the London-based group ActionAid.