Nigerian troops rescued a French oil worker taken hostage by suspected ransom seekers on Friday after five weeks in captivity, authorities said.
The release of the contractor to French oil company Total means there are no foreign hostages in the world's eighth largest oil exporter for the first time this year.
A military spokesman in Rivers State, Sagir Musa, said the security agencies received a tip-off about the hostage's whereabouts.
"When we cordoned the area to rescue the French national, the gang and the joint task force engaged in a gunfight. We overpowered them, they escaped, but we were able to rescue the French national," he said.
A French embassy official confirmed the release.
A different group yesterday released two Italian hostages it had held for 98 days.
Thousands of foreign oil workers have left the Niger Delta since February last year, when a new militant group staged a series of attacks that forced Royal Dutch Shell to shut a fifth of Nigeria's oil production.
The militancy has fuelled lawlessness in the vast wetlands region, and kidnapping foreigners for ransom became an almost weekly occurrence in January and February.
Poverty and bad government lie at the root of the violence in the Niger Delta, where impoverished fishing settlements host multi-billion dollar oil facilities.