UNITED NATIONS — The international effort to stabilize Haiti is extremely fragile and becoming even more so because of soaring food prices and declining living standards that have sparked riots, the U.N. envoy to Haiti said Tuesday.

Hedi Annabi called for urgent food aid for the Western Hemisphere's poorest nation, noting that close to 80 percent of Haiti's people live on less than $2 a day and are seriously affected by the global increase in prices for basic food items.

The unrest began last week when Haitians burned cars and attacked a U.N. police base in the southern city of Les Cayes, killing at least five people. The protests spread this week to the capital, Port-au-Prince.

"I think we have made progress in stabilizing the country, but that progress is extremely fragile, highly reversible, and made even more fragile by the current socio-economic environment," Annabi told reporters after briefing the U.N. Security Council.

"I think there is a need for urgent assistance to alleviate the suffering of the population," he added. "At the same time, we need to remain vigilant and respond robustly so that we do not allow these demonstrations to be exploited by people with political motivations or by people belonging to various camps."

Though economic growth has returned to a 1991 level of 3.2 percent a year and inflation declined to 8 percent in 2007 from 30 percent-40 percent a few years earlier, Annabi said there has not been any improvement in difficult living conditions of the vast majority of Haitians.

The cost of staples such as rice, beans, fruit and condensed milk has gone up 50 percent in the past year, while the cost of pasta has doubled.

The U.N. World Food Program made an urgent appeal Monday for donations to support its operations in Haiti. U.N. Secretary-General Ban Ki-moon warned last week that the food crisis could threaten security in Haiti.

Annabi said the 9,000-strong U.N. peacekeeping force should not be reduced when its current mandate expires in October. The force, which costs member states $535 million annually, has been in place since a 2004 rebellion that led to the ouster of President Jean-Bertrand Aristide.

UN envoy warns that rising food prices threaten to undo progress toward stabilizing Haiti.