IWUO-OKPOM, Nigeria (AP) — The brown spots run like a trail of blood down the deserted coastline near this fishing village. Just underneath a handful of sand lies spilt oil.

Oil powers this West African nation's economy but is killing its southern shores. Villagers here say the spillage regularly washes ashore, ruining their fishing nets and meagre livelihoods. Children whose parents can't afford school fees pass the time flipping bottle caps into tin cans.

While the world is transfixed by the BP disaster in the Gulf of Mexico, oil spills have become a part of everyday life during the 50 years that foreign firms have been pumping out Nigeria's easily refined fuel. Environmentalists estimate as much as 550 million gallons of oil have poured into the Niger River Delta during that time — at a rate roughly comparable to one Exxon Valdez disaster per year.

Black crude stains the coasts of the Niger Delta, a region of swamps, mangroves and creeks almost the size of South Carolina or Portugal. But who is responsible, and who should clean up? The answers are as murky as the fouled waters.

"They pay when they spill in their own country. All those oil companies come from white-man countries," said Samuel Nyrdi, a pastor and fishermen's representative. "In our country now, they leave the fishermen in pain."

Colonised by the British in the late 1800s for its palm oil, Nigeria became an oil power after Royal Dutch Shell struck its first working well in 1956 in the Niger Delta. Other foreign firms moved in, among them Chevron Corp., Italy's Eni SpA, Exxon Mobil Corp. and French major Total SA, all working across the delta in partnership with the state-run Nigerian National Petroleum Corp.

Much of the oil heads to the US.

Opec figures put daily production at about two million barrels. But the profits come at a steep ecological price.

According to government figures, Nigeria suffered more than 6,800 oil spills from 1976 through 2001, losing some 130 million gallons — 3 million barrels.

Under the worst-case scenario, the Gulf Coast spill is sending 2.5 million gallons a day into the ocean where the offshore rig Deepwater Horizon exploded on April 20.

Environmentalists say the Nigerian government figures don't include what is lost in attacks by militants demanding a bigger share of the profits for the delta region, and in communities too remote or dangerous to enter.

In Iwuo-Okpom, an Atlantic Ocean village of 7,000, a tiny flame on the horizon marks an offshore Exxon Mobil oil platform. On this coast, in January 1998, a pipeline of the company then known only as Mobilebroke and spilt about 1.6 million gallons into the ocean, one of Nigeria's worst spills. The slick spread as far as Lagos, a city of 14 million people, 120 miles northwest.

Tadef Amuwa, a 35-year-old woman who smokes fish in Iwuo-Okpom, says those caught near the village cook poorly.

"All these things, they all go black," she said, sweeping her hand across oil-soaked driftwood and puny, discoloured fish.

In a statement, Exxon Mobil's Nigerian subsidiary said it used aeroplanes and boats to spray dispersants on recent slicks, though "regrettably some oil did reach shoreline areas". The subsidiary said it also offered contracts for locals to help with the clean-up. Village leaders denied receiving any such offers.

More than 4,300 miles of pipelines and flow stations snake through the delta, some of them decades old, corroded and prone to failure under the pressure.

Oil companies can't be blamed for all the spills. Militant groups have targeted pipelines, kidnapped oil workers and fought government troops here since 2006. Fearing attacks and kidnappings, firms are hesitant to send staff to spill sites, and often confine employees to offshore platforms and military-protected compounds.

In Ogoniland, a swampy, oil-rich portion of the delta, villagers rebelled and drove out the oil companies in the 1990s. Still, Shell pipelines run throughout the area.

As the tide ebbs at Bodo City, a town in Ogoniland, exposed mangrove roots drip black from spilt crude. There are no birds in the sky or fish in the creeks.

"They died," said Mike Vipene, a youth leader in Bodo City. "They won't be coming back."

Villagers blamed a failing Saell pipeline. Caroline Wittgen, a Shell spokeswoman, said the company wouldn't comment on individual spills. A recent Shell environmental report said that almost all the oil spilt from company limes last year — more than four million gallons — resulted from sabotage.