Nigerian battle militia fighters after new attack on Royal Dutch Shell oil platform

Nigerian troops battled militia fighters in swamps around a Royal Dutch Shell oil platform that militants attacked at dawn, the third assault on Shell oil facilities in less than a week in the troubled region.

Soldiers guarding the Benisede facility in the southern, oil-rich Niger Delta returned automatic weapons fire, but it was unclear if they had lost control of the oil platform, said Brig. Gen. Elias Zamani, commander of a special task force charged with security in the volatile oil region.

Zamani had no other details of the fighting and said the military was investigating. But a military official who spoke on condition of anonymity because he is not authorized to speak to the media, said there had been casualties on both sides.

A Shell spokesman confirmed the attack and said the company has begun evacuating oil facilities in the area considered vulnerable to attack. He spoke on condition of anonymity, because he was not authorized to speak to the media about the incident. He had no word on casualties.

Residents of the area reported continuous gunfire and the explosion of heavy guns for most of Sunday after troop reinforcements moved in.

Another resident, Nelson Wariebi, said he had seen military helicopters moving in to attack positions held by the militants. On Wednesday, gunmen attacked Shell's EA platform in shallow waters near the delta coast, seizing a Bulgarian, an American, a British and a Honduran. A major Shell pipeline leading to its Forcados export terminal was blown up the following day.

Though Shell resumed some production cut last week, the first two attacks initially forced a 10 percent drop in Nigeria's oil exports.

A previously unknown militant group, Movement for Niger Delta Emancipation, claimed responsibility for first two attacks, warning all Western oil companies to leave the Niger Delta for their safety and calling on the government to release militia leader Mujahid Dokubo-Asari.

Dokubo-Asari campaigned for secession and greater local control of oil wealth before he was jailed in September and charged with treason, the AP reported.

Nigeria is Africa's leading oil exporter and the fifth-biggest source of U.S. oil imports. The country produces about 2.5 million barrels a day. Violence, hostage-taking and sabotage of oil operations have been common in the oil-rich Niger Delta in the past 15 years amid demands by the region's impoverished communities for a greater share of the oil revenue flowing from their land.