Two oil pipelines owned by Royal Dutch Shell are burning for a fourth consecutive day in southern Nigeria's Port Harcourt area.
A company spokesman said firefighters have not been able to access the burning pipelines.
Both fires started Sunday in the Ogoni region of Rivers State.
A company spokesman said it is not clear how the blazes started. He said, so far, the fires have not disrupted oil exports from the oil-rich Niger Delta region.
Nigeria produces more than two million barrels of oil per day.
But violence against the oil industry in the oil-rich south has reduced the country's output by about 20 percent. Many of those attacks have been carried out by militants demanding that locals get more of the region's oil wealth.
However, gangs seeking ransom have also carried out some of the attacks.
Some information for this report was provided by AFP and Reuters.