Dozens of U.S. soldiers surrounded Haiti's main prison on Sunday after inmates, angry at delays in the judicial process, threw rocks and set fires. At least six prisoners were injured.

U.S. troops were not involved in quelling the riot, which broke out late Saturday and died down before dawn. They cordoned off the area with barbed wire but cleared the street at midday Sunday.Many of the 520 inmates at the national penitentiary were angry that they had been in jail for minor offenses, some for over six months, without seeing a judge, said Raymond Kelly, head of the international police monitoring force in Haiti.

"There was only a small number of people convicted of anything," said Kelly, the former New York City police commissioner. "People have languished there for a long time. Judges have not processed the cases."

Although U.S. soldiers returned elected President Jean-Bertrand Aristide to power Oct. 15, Haiti's justice system remains in disarray after three years of military rule. International advisers are helping revamp the courts and police force.

At least 15 prisoners escaped during the disturbance, Kelly said.

The riot was sparked after a scuffle as prisoners were being led into a large cell, Kelly said. Guards on a walkway fired shots, injuring one person and prompting inmates to set a fire in the chapel.