In last month's attacks, heavily-armed fighters bombed several oil pipelines, sabotaged production platforms and crippled one of the main tanker loading platforms, all located on the western side of the vast wetlands region.
The group has vowed another large-scale attack on oil facilities in another area of the delta, and repeated the threat on Wednesday, advising foreign workers to leave.
``We will attack the most heavily fortified installations so the Nigerian government cannot claim to have been caught unawares,'' they said.
Royal Dutch Shell has evacuated its staff from the entire western delta, cutting 455,000 barrels per day (bpd) of its own output and 100,000 bpd pumped by other companies.
Western multinationals in the eastern delta, including ExxonMobil, ENI unit Agip, Chevron and Total are on a heightened state of alert.
And from the Atlantic (via Gristmill):
With an ethnically and religiously combustible population of 130 million, Nigeria is lurching toward disaster, and the stakes are high -- for both Nigeria and the United States. An OPEC member since 1971, Nigeria has 35.9 billion barrels of proven petroleum reserves -- the largest of any African country and the eighth largest on earth. It exports some 2.5 million barrels of oil a day, and the government plans to nearly double that amount by 2010. Nigeria is the fifth-largest supplier of oil to the United States; U.S. energy officials predict that within ten years it and the Gulf of Guinea region will provide a quarter of America's crude.
It is hardly surprising, then, that since 9/11 the Bush administration has courted Nigeria as an alternative to volatile petro-states in the Middle East and Latin America. In 2002, the White House declared the oil of Africa (five other countries on the continent are also key producers) a "strategic national interest" -- meaning that the United States would use military force, if necessary, to protect it. In short, Nigeria's troubles could become America's and, like those of the Persian Gulf, cost us dearly in blood and money.
[Nigerian president Olusegun] Obasanjohas has shown scant appetite for tackling the crime, neglect, and inefficiency rampant in the oil sector. "Bunkering" -- tapping into pipelines and siphoning oil into makeshift tankers hidden in the swamps of the Niger River Delta -- is widespread; it is responsible for the loss of some 200,000 barrels a day and for catastrophic fires that have incinerated locals attempting to scoop up the runoff. Criminal gangs with government connections are said to be behind the practice -- who else could hire the needed equipment?
During his first term, Obasanjo established a development commission to distribute oil revenues among the country's indigenous peoples, but its efforts have come to naught; most of the windfall oil profits of the last few years have gone toward refurbishing mansions for the elite. Oil spills and gas flares blight the delta, ruining farmland and poisoning fishing grounds. Owing to the abysmal state of its few refineries, Nigeria remains an importer of gasoline. Officials divert gas from the pumps and sell it on the black market. Fuel shortages are endemic.