One person was killed and another wounded in an attack on an oil facility by unidentified gunmen off the coast of southern Nigeria early Thursday, a navy spokesman said.

"I can confirm there was an incident off the coast of Akwa Ibom State, the captain of a security vessel was killed and one crew member wounded," Commodore David Nabaida told AFP.

He said the attack took place in the early hours.

Nabaida said a storage facility belonging to Addax Petroleum had come under attack. According to him, the navy boarded an Addax service vessel and an exchange of fire with the attackers ensued.

Addax in Nigeria said they were still investigating. Staff at its Geneva offices were not available and spokespeople in Toronto, where the company is quoted, and in London had no information.