Rebels from Nigeria's oil-producing Niger Delta on Thursday claimed responsibility for the attack on Royal Dutch Shell's Bonga oilfield and the kidnapping of an American oil worker.
More than 200 foreigners have been abducted, and mostly released in exchange for money, in the region where crime and militancy surged until late 2007 when there was a lull.
Below is a chronology of some major attacks and kidnappings in Nigeria's oil delta.
July 5, 2007 - A 3-year-old British child, Margaret Hill, is abducted in Port Harcourt. She is released on July 8.
-- July 7 - Oil major Royal Dutch Shell says one of its teams was attacked in Rivers state and two Nigerian workers taken hostage. The Nigerians are released on July 11.
-- July 12 - Francis Samuel Amadi, the 3-year-old son of a traditional ruler in the community of Iriebe, is kidnapped near Port Harcourt. He is released the next day.
-- August 8 - Kidnappers release a Bulgarian and a Briton, employees of British oil company Exprogroup. They were abducted on July 8 from a barge near Calabar in Cross River state.
-- August 28 - A Pakistani manager at a construction site run by Italian firm Gitto is released. He had been kidnapped on July 31 near Bodo in the Ogoni area of Rivers state.
-- September 23 - Movement for the Emancipation of the Niger Delta (MEND) says it will recommence attacks on oil installations and abduction of expatriates following the arrest of leader, Henry Okah, on arms trafficking on September 3.
-- October 5 - David Ward, a British manager from oil services firm Hydrodive in Port Harcourt, kidnapped on August 10, is freed by Nigerian troops.
-- October 10 - A Colombian and a Filipino, kidnapped on September 27 in a raid on oil services company Saipem, are released. A Colombian colleague was shot dead during the abduction.
-- Oct 20 - Seven workers, four Nigerians and three contractors to Royal Dutch Shell, a Russian, a Briton, and a Croat, are kidnapped at the EA field off the coast of Bayelsa state by gunmen in speedboats. All are freed two days later.
-- Oct 30 - Six Indian and Polish hostages, seized on October 26, are freed. They were taken from the Mystras vessel, an offshore oil production facility operated by Saipem. MEND had claimed responsibility for the attack.
March 4, 2008 - A German employee of German-Nigerian construction group Julius Berger, an arm of Bilfinger Berger AG, is kidnapped between the Rumuji and Emuoha areas of Port Harcourt. He is released around 12 hours later.
-- May 23 - Two foreign employees of oil services company Lonestar -- one from Pakistan, the other from Malta -- are kidnapped at Omoku in the Niger Delta.
-- June 3 - Gunmen kidnap two Lebanese employees of Setraco, a local engineering company, near the town of Amassoma.
-- June 19 - MEND rebels claim responsibility for an attack on Royal Dutch Shell's Bonga oilfield off the coast of Nigeria. The rebels warned of further attacks and kidnapped Jack Stone, the U.S. captain of a nearby supply ship.
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(Writing by David Cutler, London Editorial Reference Unit)