A Nigerian rebel group on Thursday seized and then released six foreign nationals who were working on an oil production vessel run by Italian energy group Eni in Nigerian waters.
The six technicians held for several hours by the Movement for the Emancipation of the Niger Delta (MEND) included two Croats, a Briton, a Romanian, a Pole and an Australian, Eni said.
The hostages were taken from a ship operated by Eni subsidiary Saipem in the Okono oil field about 55 miles out to sea from Port Harcourt.
Armed guerrillas attacked the vessel early on Thursday.
Announcing the hostage's release, MEND indicated that it wanted no more hostages than the ones it already held.
The group took six other hostages in the state of Bayelsa on Tuesday during a raid on an oil field operated by American group Chevron in the state of Bayelsa in the Niger Delta.
These hostages - four Italians, a Croat and an American - will be freed on May 30 as long as the state government does not try to obtain their release by paying a ransom, MEND has said.
MEND kidnapped three Italians working for Eni in December and later released them unharmed. The group is demanding that the oil-rich region Niger Delta be given independence and that money from oil be used to reduce poverty locally. It has been waging a two-year campaign of kidnappings and attacks on foreign oil firms in the area.
Its attacks last year shut down a fifth of Nigerian oil output. Nigeria is Africa's biggest oil producer and the sixth largest in the world.
The group says it wants the impoverished local population to have a share of the region's oil profits and say the oil industry must compensate the people for the environmental damage it has caused.
However, some observers say that many militants who claim to be fighting to improve the plight of the local population are really little more than oil thieves, bandits or the puppets of corrupt politicians.
