Nigerian military forces stormed the hideout of a militant gang operating on the waters of oil-producing Cross River State and rescued 27 abducted oil workers, a navy spokesman said Sunday.

"It was a joint military operation involving the navy and the army. Twenty-seven oil workers were rescued on Friday, while one is still missing," Lt. Commander Ajibola Olabisi told AFP.

He said 28 workers of Sinopec, an oil-servicing company, had been kidnapped on Thursday in Ikang near the state capital Calabar by an armed gang called the Lactop Marine Force.

Olabisi said members of the gang had been terrorising residents of the area for a long time before the troops moved in to dislodge them.

"The criminals fled as soon as our men stormed their hideout. Nobody was either killed or injured during the operation," he said, adding that the military were on the trail of the kidnappers.

For several years, Nigeria's oil-rich Niger Delta was hit by militant attacks until a 2009 amnesty deal sharply reduced unrest in the region.

The militants that operated there were notorious for kidnapping foreign and local oil workers for ransom. Despite the amnesty, sporadic incidents continue to occur.

Unrest in the region had curbed oil production in Nigeria, Africa's top oil producer and the world's eighth largest, to less than one million barrels per day, but output has recovered since the amnesty to more than two million barrels.