Oil giant Shell has been forced to delay shipments of Nigerian crude after an apparent dynamite attack on one of its main pipelines in the country.
Nigeria's oil pipelines are often attacked
The attack by unknown gunmen killed at least eight people, and is expected to delay deliveries of more than 180,000 barrels per day for up to a week.
After the incident, Shell had to shut down two wells that supply the pipeline in the main Niger Delta oil region.
Pipelines have been attacked in the region a number of times before.
Some residents in the Niger Delta area have long claimed they do not benefit from the oil wealth, leading to the attacks.
In other instances, pipelines have been cut by thieves to siphon off the oil.
Anglo-Dutch Shell has involved "force majeure" to formally delay the shipments of oil.
This is a legal term allowing a company to release itself from a contract due to unforeseen circumstances out of its control.
The attack occurred 50km (31 miles) west of the oil centre of Port Harcourt, said Shell, hitting its Bonny terminal.
"There is a team on site now which has boomed off the oil spill, a fire-fighting crew has been mobilised as well to put out the fire," said a Shell spokesman in Nigeria.
"We have shut down [the] Bonny flow station in order to enable us to contain the fire, which is still raging, and carry out repairs.
"We are cutting back the production and exportation and it also means that we won't be able to provide all the crude we were supposed to."
The attack, which will cut total Nigerian oil exports by 7%, has had a knock-on effect on global oil prices, with both US light crude and the UK's Brent rising.
A previously unknown militia group calling itself the Martyrs' Brigade has claimed responsibility for the attack.
Andoni region local government chairman Monwan Etete said youths in four speed-boats had warned residents of local fishing villages to leave their homes shortly before the attack on Monday night.
Nigeria is the world's eighth largest oil producer, and the largest in Africa.