US Marines thought they saw two dead on the ground after one clash but found no bodies when they returned to the scene later, said Major Richard Crusan, a US military spokesman. He said it was possible the attackers may have removed the bodies.

"There were three incidents last night where gunmen fired at Marines who in all three cases returned fire," Crusan said, also mentioning another attack where Marines did not return fire.

US forces suffered no casualties, said the spokesman.

He said he was not sure whether outgoing prime minister Yvon Neptune was at the residence, which eventually will be occupied by lawyer and economist Gerard Latortue, named Tuesday to head a new Haitian government.

"In the first incident a Marines patrol came under fire from multiple gunmen" about 800 meters (875 yards) from the residence, said Crusan adding that the shooting started at 6:43 pm (2343 GMT).

"Initial reports from the Marines said there were two male Haitians killed, but they did not stop to collect the bodies. They secured the area, notified Haitian National Police and returned to the prime minister's residence."

The Marines returned to the scene with police officers more than three hours later, and found blood, impact marks and empty casings. "No bodies were found," said Crusan, adding: "It is possible they were removed" by the attackers.

"At that time, the squad and Haitian National police were again engaged by hostile fire, and the Marines broke contact and returned to the residence."

"At 23:05 (0405 GMT Wednesday) multiple rounds of automatic weapons were directed again at the prime minister's residence. The gunfire seemed to come from a spot 300 meters (328 yards) from the residence," he said.

US Marines also came under attack outside the city's main port, where they have established a presence to prevent further looting.

"At 22:58 pm (0358 GMT Wednesday) a vehicle driving at high speed approached Marines," the military spokesman said. "A number of rounds were fired, though it was not clear if they were directed at the Marines," he said.

The vehicle came to a halt near the main gate of the port, at least one person got out and "fired in all directions and then fired at the Marines. The Marines returned fire."

"Three individuals then fled on foot," he said.

"No casualties were reported," said Crusan.

US Marines had been involved in several firefights in recent days, killing a man they said was shooting at the presidential palace and another who failed to stop at a military roadblock.

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