LAGOS, Nigeria -- Gunmen armed with dynamite assaulted a Chevron Corp. tanker in Nigeria's southern oil-producing region early Tuesday, killing a Nigerian sailor and kidnapping an American oil worker and five other foreigners, authorities said.
The restive region's main militant group, the Movement for the Emancipation of the Niger Delta, claimed responsibility for the attack.
Navy Capt. Obiora Medani said the sailor was a guard aboard the tanker FPSO Oloibiri, which was in waters off Bayelsa state.
Chevron said it shut down a station pumping oil to the ship, cutting its daily production by 15,000 barrels.
Tope Idowu, a spokesman for the California-based company, said the gunmen kidnapped an American, four Italians and one Croatian. He said the American worked for Chevron in Nigeria while the rest were employees of a subsidiary, Chevron Shipping Co.
No demands had been made by the attackers, Idowu added.
The claim of responsibility was sent from an e-mail address used by the Movement for the Emancipation of the Niger Delta. It said the attack was to demonstrate the group's continued strength as the West African nation ushers in a new government after recent elections.
"We will continue with our struggle for justice until we achieve all our goals without exception," the group said.
The group promised to release the hostages May 30 as long as there was no attempt to free them -- such as offering a ransom. It previously has demanded the release of two leaders imprisoned by the government on treason and corruption charges and it wants the Niger Delta's people to have greater control over the region's oil wealth.