An oil flow station operated by Royal Dutch Shell in southern Nigeria was on Sunday attacked by unidentified ethnic militants, leaving some people injured, a company spokesman told Xinhua.
"Some people were injured during the attack. I don't have the number, but we have moved to (the oil city of) Warri for medical attention," said the spokesman. "The Benisede flow station ( attacked) has been shut since January 11," he added.
The Benisede flow station was one of the four facilities closed on Wednesday after local militants vandalized a major pipeline feeding the Forcados terminal. The attack forced Shell to cut production of 106,000 barrels of oil per day, or five percent of Nigeria's total output.
On the same day, armed men, riding in three boats, stormed Shell's EA oil field in the Atlantic Ocean, taking hostage four workers, a Briton, an American, a Bulgarian and a Honduran who were working for the firm's two subcontractors, Tidex and Ecodrill.
The four were still being held by the alleged kidnappers, a previously unknown group, who calls itself the Movement for the Emancipation of the Niger Delta.
The group said that they were not out for cash ransom but to bring the issues of resource control in the impoverished delta, where the majority of Nigeria's oil is produced, to the front burner.
The group also demanded the release of Diepreye Alamieyeseigha, former governor of Bayelsa state who was impeached and arrested in December for money laundering, and Mujahid Dokubo-Asari, a local ethnic militia leader who faces treason charges.
"We are capable and determined to destroy the ability of Nigeria to export oil or other petroleum products for that matter, " the group said in a statement to the media.
"For the safety of its citizens, the United States and other European nations with citizens on our soil will do well to advise these individuals to leave immediately."
Nigeria is the biggest oil producer in Africa with a daily output of 2.5 million barrels, while Shell accounts for half of the country's oil production.