Thousands of civilians and gunmen pillaged oil and sacks of grain from Monrovia's (searchport Wednesday ahead of rebels' promised withdrawal, and the United States pledged 200 troops to bolster West African peacekeepers.

A ship laden with humanitarian aid bobbed offshore, ready to deliver food and supplies to civilians starving and facing disease in the besieged capital, where many have subsisted on leaves.

After Charles Taylor's (searchdeparture, rebels promised U.S. and other officials they would withdraw from the port and the rest of Monrovia by noon Thursday. If that happens, aid workers could begin bringing in supplies within days, U.N. deputy emergency relief coordinator Carolyn McAskie (search) said.

The U.S. force would be the largest sent ashore despite international pressure for the Bush administration to help the wartorn West African nation, founded in the 19th century by freed American slaves.

Fighting persisted Wednesday outside Monrovia, even after the resignation Monday of Taylor, the warlord-turned-president whose exile in Nigeria was seen as a step toward ending 14 years of near-incessant bloodshed.

Three U.S. warships carrying about 2,300 Marines already await off shore, and the Pentagon said some 200 American forces would be sent in if the rebels surrender the port.

U.S. forces would include elements to work with the peacekeepers, Navy SEALS to help secure the waterway and engineers to assess the port for delivery of humanitarian supplies, the Pentagon said.

Government forces and fighters of Liberia's smaller rebel movement battled on the road leading from Monrovia to the southeastern port of Buchanan. West African peacekeepers and others said clashes were at least 60 miles from the capital.

Insurgents fighting for three years to oust Taylor pressed their siege of the capital in the past two months, spurring urban mortar barrages and gun battles that have killed more than 1,000 people and displaced hundreds of thousands.

The fighting has split the capital into the government-held downtown and the rebel-held port, which is controlled by the larger of Liberia's two rebel groups. Government areas have been unable to get food from the port, leaving trapped civilians in Monrovia's government territory famished and eating little but leaves.

Mainly young men but also girls and the elderly joined fighters streaming out of Monrovia's port Wednesday with sacks of grain, cooking oil and other goods taken from shipping containers and international aid agency warehouses.

After hours of pillaging, rebel commanders ordered looters out of the port.

"We are totally in control of the situation," said rebel official Sekou Fofana as his troops -- mostly child fighters -- kicked, beat, and fired guns over the heads of throngs carting off bags of food, many marked with U.N. and World Food Program seals.

"This is for my family across the river," explained Jerry William, a civilian carrying a bag of bulgur wheat on his head.

Rebel leaders denied their men were looting.

Liberia's main rebel group has held the port since the third week of June, halted at the city's front-line bridges while government fighters hold downtown.

Rebels, intent on keeping government troops from retaking the port, have insisted that peacekeepers be in place Thursday to secure it.

West African peace troops began landing in Monrovia on Aug. 4, though only about 800 have arrived so far, most of them Nigerian. Based at the airport outside the city, they have made only brief forays into Monrovia.

A second, 776-member battalion of Nigerian forces will start deploying Thursday, Nigerian army spokesman Col. Chukwuemeka Onwuamaegbu said.

U.S. troops would be welcome to help prevent gunmen from threatening aid workers. Many more peacekeepers are needed to "provide support to humanitarian workers," U.N. relief worker McAskie said.

Looters briefly stopped plundering Wednesday to glance up as U.S. military helicopters whirred over the capital.

One carried vehicles in a sling, though it was unclear where it landed. U.S. Embassy officials wouldn't discuss the helicopters' mission, although they confirmed that Ambassador John Blaney had permission for the flight from Liberia's new president, Moses Blah.

In an interview with The Associated Press, Blaney said he believed Liberia's new leader to be "sincere in his desire for peace" and said the United States was committed to ensuring that the peacekeeping mission would be successful.

"America will be here and we're going to guarantee that this is going to be a success," Blaney said, declining to comment on specifics of the American role.

"We don't anticipate any problems," he said, stressing that rebels gave their word they would abandon the port and other rebel-controlled areas.

"We want to be here for the Liberian people."

As peace forces prepared to move into the capital, Liberia's government and the smaller, southern-based insurgency traded blame for Wednesday's fighting south of Monrovia.

Rebel representative Boi Bleaju Boi said his forces had fallen back to show that they had no intention of taking Liberia's key airport, but that government forces were attacking them. Boi spoke in Accra, Ghana, site of Liberia's sporadic peace talks.

Government representatives denied instigating the fighting, saying they hoped for the war to end after Taylor stepped down, as rebels wanted.

"For us, the war should be over by now," said Liberia's deputy defense minister, Austin Clarke.

Refugees fleeing toward the capital earlier said rebels were attacking civilians and targeting men of fighting age, raising fears that they may be seeking a share of power after Taylor's resignation.

West African nations negotiated the ex-warlord's departure and pledged to commit troops to a peace force after rebels began their drive into Monrovia in June.

His exit raised hopes of an end to years of conflict begun in 1989 when Taylor launched Liberia into civil war. He also faces a U.N.-backed war crimes indictment for his trafficking with a vicious rebel movement in Sierra Leone.

Blah will cede power in October to a transitional government that will preside over elections.