Gunmen ambushed an Indian-owned oil barge on Tuesday as it was being escorted by the military through Nigeria's Niger Delta region, killing two soldiers and one crew member on the ship, a security forces spokesman said.
The ship belonging to Sterling Global Oil Resources, part of the Sandesara Group conglomerate, was fired on in the Angiama area of the delta, according to Onyema Nwachukwu, spokesman for mixed military and police brigades in the Niger Delta region.
He added that the gunmen were repelled by return fire.
"Our troops were escorting the Sterling Global Oil barge ... when they ran into an ambush. Two soldiers and one civilian were killed," he said, and three civilians on the boat were wounded. "Troops have been deployed to the area because some of the gunmen fled wounded."
There was no immediate comment from Sterling.
The swampy Niger Delta is plagued by violence of assorted militants, criminal gangs, pirates and oil thieves seeking to grab a share of the two million barrels of oil a day produced by Africa's most lucrative energy industry.
Pirates usually attack ships offshore, while oil thieves steal from pipelines in the delta's labyrinthine creeks, although with so many armed gangs riding around on speedboats, the distinction is sometimes blurred.
Many gangs are offshoots of militant groups that attacked the oil industry ostensibly for political reasons during a decade of unrest in the delta, before a 2009 government amnesty.
The amnesty formally ended the conflict, but criminal networks continue to operate.
Suspected Nigerian pirates have hijacked a French-owned Luxembourg-flagged tanker along with its 17-member crew off Ivory Coast, Ivorian officials and the International Maritime Bureau said on Monday.
(Reporting by Tife Owolabi; Writing by Tim Cocks; Editing by Mark Heinrich)