Nigeria's army has arrested a suspected militant gang leader and more than 50 of his members over a recent kidnap of 19 people in the oil-rich Niger Delta.
The arrests were made during a raid on a militant camp in the nearby Rivers state, the army said.
The raid came three days after the 19 hostages were rescued by soldiers from creeks in Delta province.
Two Americans, two Frenchmen, two Indonesians and a Canadian were freed along with 12 Nigerians, the army said.
The foreigners were captured on 8 November, when gunmen attacked an oil rig belonging to London-based Alfren PLC.
A spokesman for the special taskforce, Timothy Antigha, said the gang was suspected of involvement in a string of recent kidnappings of oil workers in the region.
He said the leader of the group was known by his nickname, "Obese".
It was not immediately clear if the gang had been affiliated with Mend, a military group operating in Delta, which has claimed responsibility for some of the recent kidnappings.
Violence in the Delta region has subsided since last year, after the government and many oil militants reached a ceasefire agreement last year in exchange for cash payouts and job training.
However, a small faction of Mend has resumed the kidnappings.
In the past, militants have cut the country's oil production by one-third, causing a spike in global oil prices.
Mend says it is fighting so that more of Nigeria's massive oil wealth is used to benefit the Niger Delta area which produces the oil.
But criminal gangs have taken advantage of the region's instability to make money from ransoms paid by oil companies, and stealing oil.