Nigerian police said a foreign oil worker was kidnapped by armed men Thursday morning from a Royal Dutch Shell gas plant.

The hostage-taking was the second in less than 24 hours in Nigeria's chaotic, oil-rich southern delta. Late Wednesday, a group of gunmen raided an offshore oil rig and seized a security guard as they retreated, according to the Nigerian navy.

CountryWatch: Nigeria

Hafiz Ringim, police commissioner for Bayelsa state, said Thursday's kidnappers arrived at the Shell plant in speedboats and took hostage an expatriate working for Westminster Dredging, a contractor to Royal Dutch Shell. The plant is located outside of Yenagoa, the regional capital.

Ringim did not provide the worker's nationality and did not say if there was any connection between the two incidents.

The attackers Wednesday forced their way onto a rig drilling for Nigerian company Consolidated Oil and kidnapped a retired navy officer working as a security guard, said navy spokesman Captain Obiora Medani said.

Medani said the attackers told Consolidated Oil that they came from nearby Sangana community. The group is accusing the oil firm of not meeting the terms of an agreement to help provide them with jobs and local amenities, he said.

Officials of Consolidated Oil were not immediately available for comment.

Kidnappings in the restive and impoverished Niger Delta have been common in recent months with militants using the hostages to bargain for a greater share of the wealth from Africa's largest crude producer.

Attacks on oil pipelines and kidnappings, most of them by the largest militant group — Movement for the Emancipation of the Niger Delta — have cut Nigerian oil production by more than 20 percent this year, adding to the upward pressure on world prices.

Some groups have asked for money and others for freedom for imprisoned comrades. Most of the kidnappings have ended peacefully.