Dozens of soldiers in camouflage fatigues control security in this coastal city of 125,000 people. They carry automatic weapons, and their base is a former police headquarters with a freshly painted sign that reads, "General Headquarters of the Haitian Armed Forces."

The trouble is, the Haitian Armed Forces don't officially exist.

The force, which arrived in late August and chased away the town's eight police officers, includes mainly former soldiers from the army, disbanded by former president Jean-Bertrand Aristide in 1994. The men were also part of the armed rebellion that led Aristide to resign in February and flee the country. Now they are demanding that the new government reconstitute the army and have appointed themselves the law in Petit-Goave and a handful of towns across Haiti.

"We are determined to make our voice heard," said Felix Wilso, a spokesman for the soldiers in this city 40 miles west of the capital, Port-au-Prince.

The fact that an unofficial army controls Petit-Goave, unchallenged by the government and U.N. peacekeepers, illustrates how volatile Haiti remains eight months after Aristide's departure. The interim prime minister, Gerard Latortue, said in an interview that his U.S.-backed government was struggling to maintain order in the hemisphere's poorest nation.

"We are just trying our best to keep the country alive," Latortue said. "It is a miracle that we have been able to keep peace. It is a miracle that we are where we are now."

The national police force of 2,500 officers is outmanned and outgunned by groups of ex-soldiers and armed gangs that control many areas of this country of 8 million people. U.N. officials said fewer than half of the 8,300 U.N. soldiers and police promised in April had arrived and that the current force was insufficient to guarantee order in the country.

Adding to the unrest and misery, Haiti has also been battered by devastating natural disasters since Aristide left. Floods in May killed at least 1,300 people, and a tropical storm last month killed about 3,000 more.

The nation remains bitterly divided between supporters and opponents of Aristide, who is in exile in South Africa. That has resulted in a new round of political violence that has left 46 people dead in the past two weeks, including five policemen, three of whom were beheaded. Two U.N. soldiers have been shot and wounded in recent days, the first casualties since the force arrived this summer.

The U.N. troops took over from a contingent of 1,000 U.S. Marines, who had arrived in February following several weeks of fighting between rebels, most of whom were former soldiers, and armed gangs loyal to Aristide. At least 300 people died in the fighting. It was the second U.S. military action in Haiti in a decade; in 1994, 20,000 U.S. troops restored Aristide to power after he had been ousted in a military coup in 1991.

U.S. confidence in Aristide slipped after he was reelected in 2000. The president was dogged by allegations of corruption, although his allies said the Bush administration was demonizing Aristide, a populist former Catholic priest who was the first freely elected president in the country's 200-year history.

In March, a U.S.-backed council of Haitian citizen leaders appointed Latortue to lead a government until new presidential and legislative elections next year. Latortue, a former U.N. development official, was living in Florida and working as a business consultant.

International officials in Haiti say that Latortue has made important strides, winning pledges of just over $1 billion in aid, including $230 million from the United States, at a conference in Washington in July.

Latortue's government has been responsible for some basic improvements in quality of life, such as better trash collection on Port-au-Prince's filthy streets. With help from the United States and Canada, it is also providing electricity for about 14 hours a day in the capital, up from two or three hours a day when it took over.

Latortue said his main problem was a lack of resources, alleging that members of Aristide's government had looted millions of dollars from state coffers. "We found the treasury at zero when we arrived," he said. He said his main hope for job creation was legislation in the U.S. Congress that would lift tariffs on some Haitian textile imports, which he said could create 50,000 jobs.

Latortue also said that international funding was just starting to arrive. "Until the money comes, what can we do?" he asked.

In the meantime, he added, the national police force is not capable of maintaining security across the entire country.

"There is a true security vacuum here," said one foreign diplomat in Haiti, citing what he called "an amazing slowness, an astonishing slowness" on the part of the United Nations to send troops and police.

"We do not have the manpower to do the job," said Adama Guindo, the deputy chief of the U.N. mission to Haiti.

Guindo said that several nations, mainly Brazil, which is leading the force, had honored their commitments, but he did not know why other nations had delayed sending promised troops and soldiers. All forces were supposed to be in place by the end of December, but that date "has slipped so much we don't know when they will arrive," he said.

Much of the current instability stems from the government's strained relations with Aristide's Lavalas political party, which draws support from Haiti's majority poor. Latortue and Lavalas leaders accuse each other of unwillingness to negotiate the party's role in the government and the upcoming elections.

The current violence started on Sept. 30, when a march by about 20,000 Lavalas supporters ended with the deaths of three police officers. Two days later, Sen. Gerard Gilles and two other Lavalas members went on a popular radio talk show to accuse the government of inciting the violence and to deny that Lavalas was behind it.

Gilles, in an interview, said police surrounded the radio station, burst into the studio and arrested him, two other legislators and his attorney. He said he was handcuffed and jailed for four days and that the other two, including the president of the Senate, Yvon Feuille, remained in jail, accused of planning the recent violence.

Gilles and Leslie Voltaire, a senior official in Aristide's government, said they believed the government had hired armed thugs to stir up violence as a pretext for cracking down on Lavalas. They also said the government feared continued calls for Aristide's return to power.

"This is a government that just wants revenge against Lavalas," Gilles said.

Latortue said he believed Gilles was a moderate, nonviolent man whose arrest was a mistake, but that police had claimed to have evidence that Feuille had organized the violence.

In another sign of escalating tensions, the Associated Press reported Wednesday that Remissainthe Ravix, who commands the Petit-Goave soldiers, and other ex-military leaders were planning to enter the capital to help end the recent outbreak of violence, setting up a potential confrontation with police and U.N. peacekeeping forces.

In Petit-Goave, many residents interviewed said the soldiers were providing better security than the force of eight police officers had done. One recent day, at least 20 of them helped dig a drainage ditch in a severely flooded neighborhood.

Mayor Sandra Jules, 21, who was appointed by Latortue's government in August, watched the soldiers working. As she spoke with a reporter, two armed soldiers came up to listen, one of them carrying an Uzi. Jules was asked what she thought of having her town under the control of the unofficial soldiers.

"As mayor, I know this is illegal," she said, looking at the two soldiers monitoring her. "But whatever is good for the security of the people here, I accept."

Former soldiers from the Haitian army, disbanded in 1994, ousted police in Petit-Goave, west of Port-au-Prince, and now control the town.