PORT-AU-PRINCE, Haiti — Haiti's security situation is potentially volatile, the United Nations warned today, after an armed group of men attacked a food convoy.

Haitian police have increased their own patrols and are accompanying U.N. police as frustration grows at the slow pace of aid since the Jan. 12 earthquake that killed at least 150,000 people.

Most of the quake victims are still living outside in squalid tents of sheets and sticks, many forced to scramble for food and water. Mobs have stolen food and looted goods from their neighbors in the camps, prompting many to band together or stay awake at night to prevent raids.

"The overall security situation across the country remains stable but potentially volatile," the U.N. mission said in a statement today.

About 20 armed men blockaded a street Saturday and attacked a convoy carrying food from the airport in the southern city of Jeremie, according to U.N. spokesman Vicenzo Pugliese. U.N. and Haitian officers fired warning gunshots and the men fled the scene, Pugliese said. No injuries were reported and no one was hurt.

By The Associated Press