Two suspected fighters are killed at a Shell oil base in the Niger Delta.
ENI closed down its Okono/Okpoho oilfield – which produces 50,000 barrels a day – after the kidnapping, an industry source said.
Another source said the attack was “community-related”, referring to disputes between oil companies and nearby villages about employment, infrastructure and other benefits.
Dozens of mostly foreign oil workers have been seized this year but most have been released unharmed after talks involving the local government.
Nigeria – Africa’s top oil producer – has already cut output by a fifth since February, when armed groups fighting for control of the delta’s oil wealth attacked pipelines, platforms and export terminals.
The groups want to see the region receive a more money from the oil extraction that has resulted in huge revenues for the federal government and oil firms.