The remaining hostages were freed unharmed. Nigerian troops killed two kidnappers in the raid.

In this case, a floating production, storage and offtake vessel operating 55km off the coast of the Niger Delta was attacked by gunmen in speedboats. The kidnappers with the hostages in their boats ran into a military patrol, and a firefight ensued, security sources told Reuters.

Earlier, a spokesman for Eni, the Italian major operating the facility, said two Finns, a Briton, an Italian, a Filipino, a Pole and a Romanian had been taken hostage.

The British hostage was killed, while the Italian was seriously wounded, according to the Times Online. But other reports have said another hostage was also wounded.

Dozens of mostly foreign oil workers have been seized this year by ransom-seekers and politically motivated militants.

While this is the first time an expatriate oil worker has been killed after being taken hostage in Nigeria, in August one Nigerian oil worker was killed by troops trying to free him.

Eni has reportedly closed down its 50,000 barrel a day Okono/Okpoho oil field as a result of the attack, according to Reuters.

Nigeria – Africa’s leading oil producer and exporter – has already cut output by between 20% and 25% since February, when militants fighting for regional control of the delta’s oil wealth staged a series of attacks on pipelines, platforms and export terminals.