President Olusegun Obasanjo ordered stepped-up protection for pipelines after a gasoline blast killed up to 200 people, but Nigerians said Saturday that impoverished villagers would keep tapping the pipes to pilfer fuel.
Rescue workers tried to finish collecting the dead for burial in mass graves by sundown. But at least 22 charred bodies floated in the tidal mangrove swamps east of the main city of Lagos - miles from the site of Friday's disaster in Ilado village.
Police said there was no sign that the fire at a ruptured pipeline was sabotage and they assumed villagers had punctured it to steal fuel. They said 150 to 200 people died in the flames when the gasoline ignited.
Obasanjo, who was on a state visit to Indonesia, ordered an investigation into the cause of the inferno, Radio Nigeria reported. He also called for increased protection of the country's vast web of pipelines, the radio said.
But Nigerians said little could keep poor villagers from rupturing the pipelines that are ubiquitous across Nigeria's south because the allure of free fuel outweighs the well-known danger. Villagers often tap pipelines to steal fuel for cooking or resale on the black market.
More than 1,000 people in Nigeria have died in recent years when fuel they were pilfering from pipelines caught fire.
"This has been going on for a long time. Those people were just unlucky they caught fire this time," said Hakim Bolaji, 32, a boat driver who plies the swamps. "People are making so much money from selling stolen petrol that I'm sure they'll come back."
The blaze took place far from the center of the fishing village of Ilado, and it was unclear if there were witnesses. Boatsmen said they heard an explosion before dawn and saw the glow of flames.
Nigeria, which normally pumps 2.5 million barrels of crude a day, is Africa's largest producer and the fifth-largest source of imports to the United States. Most of Nigeria's oil is pumped in the southern Niger Delta region, far from Lagos.
Despite the great wealth of Nigeria's natural resources, most of the country's 130 million people remain deeply poor.
This inequity, blamed on official corruption or mismanagement, motivates militant attacks as well as villagers' stealing of fuel they consider their birthright.
Obasanjo's order for greater security around the pipelines comes as militants in the oil region have stepped up attacks on pipelines and other petroleum-industry infrastructure, cutting production by a quarter and helping send crude prices soaring on international markets.
Friday's blast was unlikely to affect exports. The pipeline was run by Nigeria's state oil company and was used to transport gasoline used for domestic consumption.