In Haiti, security forces remain on alert, one day after an apparent coup attempt was repelled at the presidential palace.

President Jean-Bertrand Aristide says Monday's coup attempt failed, but the threat of further violence remains.

Mr. Aristide addressed his countrymen from the presidential palace in downtown Port-au-Prince. Gunmen stormed the complex early Monday, killing two policemen and two passers-by. One attacker was also killed as security forces repelled the assault.

Mr. Aristide was not in the palace at the time.

Exactly who organized the attack remains unclear. Government officials have long accused former army and police chiefs allied with Haiti's political opposition of plotting to overthrow Mr. Aristide.

Haiti's opposition coalition has denied responsibility for the attack and accused the ruling Lavalas Party of using the incident as a pretext for hunting down political opponents. Most opposition leaders have gone into hiding.

As news of the apparent coup attempt spread, hundreds of machete-wielding Aristide supporters took to the streets of Port-au-Prince. The demonstrators pledged to defend Mr. Aristide, a former Roman Catholic priest whose first administration ended with a coup in 1991.

Most international flights to Haiti were cancelled Monday, and Haiti's border with neighboring Dominican Republic has been sealed.