A pipeline supplying Nigeria's populous southwest, including Lagos, with oil products was shut down on July 22 following an explosion around midnight, the country's emergency response agency said.

The blast occurred near the town of Arepo on the edge of Lagos state as a result of a clash between groups of vandals. The National Emergency Management Agency (NEMA) said it could yet not confirm the number of casualties.

"The situation is still tense, we can't go in there to check but there has been loss of life," Onimode Bandele, the NEMA head for the southwestern region, said.

Oil is stolen from Nigerian pipelines on an industrial scale across the south, especially the oil-rich delta further east, by well-organised gangs that periodically clash.

The crude stolen via illegal taps is used locally in hundreds of make-shift refineries or loaded onto barges for international export.

President Muhammadu Buhari said on July 22 that around 250,000 barrels per day of the country's crude is stolen and vowed to trace and recover the "mind-boggling" sums taken from the sector.

Nigeria is Africa's biggest crude producer with an output of around 2 million bpd and has been hit hard by the fall in global oil prices as the government depends on oil sales for about 70 percent of its revenues.