PORT-AU-PRINCE, Haiti (AP) _ The United States, which has threatened to cut aid to Haiti if dubious election results are allowed to stand, has shut down a training program for the Caribbean nation's fledgling police force.

A U.S. Justice Department spokesman confirmed Thursday that the program was closed this week, but declined to say why.

The party of former President Jean-Bertrand Aristide and his chosen successor, President Rene Preval won an overwhelming victory in the elections, the first round of which were held in May.

But the results have been called into question, and the United States, Canada and the European Union _ Haiti's biggest foreign donors _ are threatening to cut assistance.

Opposition politicians have accused Aristide, who is favored win presidential elections later this year, of using the police to further his ambitions, and the chairman of Haiti's electoral council said police helped stuff ballot boxes to fix the elections.

U.S. instructors had been training a police force with the hope of building a democratic Haiti. The program began after a 1994 U.S. military intervention restored Aristide, whom the army had ousted.

Under the program, some 5,000 police officers have been trained at a cost of $72 million. But hundreds of officers have been weeded out on charges ranging from excessive use of force to drug-dealing and murder.