A Nigerian government official says gunmen have attacked an oil pipeline operated by a Nigerian subsidiary of Chevron in the country's restive Niger Delta.
Authorities say it was not immediately known who was responsible for Friday's attack.
Niger Delta pipelines have been vulnerable to attacks in the past by militants linked to the Movement for the Emancipation of the Niger Delta, or MEND.
Hopes for a lasting peace in the Niger Delta are starting to fade as militants are starting to attack oil facilities again after a brief truce.
More than 8,000 militants had given up their weapons under a government amnesty program. But the hospitalization of Nigerian President Umaru Yar'Adua has delayed government negotiations with the region's rebels.
Some information for this report was provided by AP and Reuters.