LAGOS, Nigeria - A Canadian oil worker abducted by gunmen during an attack on an oil rig off the coast of Nigeria's southern delta earlier this month was released Wednesday after what sources said was a military operation.

Bob Croke, a St. John's, N.L, area resident was taken hostage Nov. 8 during the attack at the Okoro oilfield, 11 kilometres off the coast of Nigeria's Akwa Ibom state. The oilfield is operated by London-based Afren PLC.

Two Americans, two Frenchmen and two Indonesians were also abducted.

Foreign Minister Lawrence Cannon confirmed that Croke has been released and is now safe.

"I have ensured that through our officials he receives consular assistance and is able to be reunited with his family as soon as possible," Cannon said in a statement.

"We would like to thank everyone who worked to ensure a safe and peaceful resolution to this incident."

In a Facebook posting, Croke's niece, Danielle Croke, said she was very happy that the hostages have been freed, and her uncle is safe.

"Been holding our breath on this since it happened. Sooooooo happy he's alright," she wrote.

A Foreign Affairs spokeswoman declined to provide further details on what led to the release, saying "that might compromise or jeopardize the safe return of someone else in the future."

The French Foreign Ministry also confirmed that two French citizens were freed.

A Nigerian military spokesman said Wednesday night an operation to attack militant camps was ongoing in the region, but declined to comment further.

Sources who spoke on condition of anonymity said a military raid freed workers kidnapped from an Exxon Mobil Corp. platform this week, as well as expatriates seized in the attack on the Afren platform.

Although Croke's abduction marks the first time a Canadian oil worker has been kidnapped in the restive delta region, other nationals have been targeted in other parts of the country.

Last April, Julie Mulligan of Drayton Valley, Alta., was snatched from a road in northern Nigeria and held for two weeks before being released. Mulligan was in the country as part of a study exchange with Rotary International.

Militants in Nigeria's oil-rich Niger Delta began a campaign of kidnapping and pipeline bombings in 2006, upset over pollution and the region's endemic poverty despite 50 years of oil production.

The region's main militant group, the Movement for the Emancipation of the Niger Delta, has said it would carry out new attacks in the region after claiming responsibility for an Oct. 1 car bombing in the nation's capital Abuja that killed at least 12 and injured dozens more.

Nigerian navy vessels often offer security for offshore rigs, however there were no vessels immediately in the area when the Nov.8 attack occurred.

With files from The Associated Press