Underscoring deepening political divisions, more than 15,000 government supporters rallied outside the National Palace in the capital while about 5,000 presidential opponents marched toward downtown, shouting "Down with Aristide!"
Police fired tear gas and warning shots to scatter the crowd, and some protesters lay down before them shouting "freedom." Club-wielding police beat back a separate group of student protesters who tried to join the march, injuring at least two students and one professor.
"We will not allow Aristide to be a dictator," said protester Jean Gary Denis, 33. "He is using the bicentennial for his own purposes."
The thousands of government supporters were equally fervent, some of them knocking down a fence at the palace and scrambling onto its lawn as they crowded toward the podium, chanting: "Aristide is king!"
The bicentennial was bittersweet as some Haitians questioned whether Aristide is fit to guide the country out of its crisis.
But the president appeared confident that he spoke outside the National Palace, saying that "1804 was the stinging bee; 2004 is sure to be the honey."
Aristide listed 21 goals he hopes will be accomplished by 2015, from stabilizing the rate of HIV infection to reducing poverty. Aristide's term expires in 2006, and he didn't say whether he expects to be in office in 2015.
"It is possible to build a new Haiti because of what is on our flag, and that is, 'United we are strong,'" Aristide said.
The threat of violence hung over celebrations as flaming tire barricades went up in spots across the capital. A day earlier the charred bodies of two men were found on a Port-au-Prince sidewalk. There was no word on their political affiliation.
Some Aristide supporters were seen holding pieces of pipe and unlit firebombs Thursday.
The government spent $15 million on the celebrations, including galas, New Year fireworks and the dedication of a monument to Haiti's forefathers. But many world leaders stayed away.
Those attending festivities at the National Palace included more than a dozen foreign delegations, activists and actors including Danny Glover.
"We celebrate the Haitian revolution because it dealt a deadly blow to the slave traders who had scoured the coasts of West and East Africa for slaves and ruined the lives of millions of Africans," South African President Thabo Mbeki told the crowd. He said a "historic struggle" remains for people to overcome poverty and conflict on both sides of the Atlantic.
Bahamas Prime Minister Perry Christie called the bicentennial "a matter of great pride and symbolism everywhere."
Aristide said he is working with the opposition to bring about new legislative elections. But opponents have refused to participate and urged a boycott of Thursday's state-organized events, including another presidential speech in western Gonaives, where Haitians declared their independence from slave-holding France on Jan. 1, 1804.
Later, speaking to some 2,000 supporters in Gonaives' central square, Aristide said, "the time has come … to demand respect for the constitution, respect for everybody without distinction."
No injuries were reported Thursday in Gonaives. But gunfire the previous night wounded at least one girl and led many to take refuge.
Sporadic gunfire erupted after Aristide left, and rocks were thrown at departing cars.
Haiti was born after the world's only successful slave rebellion. On Nov. 18, 1803, French troops surrendered to forces led by Jean-Jacques Dessalines, making Haiti the first black republic and the first country in the Western Hemisphere to abolish slavery.
However, a string of leaders then drove the Caribbean country into disarray. In two centuries, Haiti has seen more than 30 coups.
There was a flicker of hope in 1990 after 29 years of the Duvalier family dictatorship. Aristide, then a slum priest making fiery promises to the poor, was elected by a landslide — only to be overthrown the next year.
He was restored in 1994 during a U.S. invasion but forced to step down in 1996 because of term limits. Now 50, Aristide has been dogged by political troubles since his 2000 re-election, largely because of legislative elections that observers said were flawed.
Since mid-September, anti-government protests have killed at least 41 people and wounded scores.
Haiti remains the Western Hemisphere's poorest country, and some blame wealthy countries for keeping it that way.
With Haiti's independence, France demanded repayment on a debt of 120 million gold francs — about $22 billion today — draining the country's coffers. Aristide said France must pay reparations.
Recently, international lenders and donors suspended more than $500 million in loans and grants after the contested legislative elections.
By Paisley Dodds And Michael Norton