Abuja - Gunmen have released a fuel tanker which was hijacked off the coast, security sources and the vessel's manager said on Wednesday.
Indian-based managers Medallion Marine lost contact with the Marshall Islands-flagged SP Atlanta on Sunday evening but resumed communication late on Tuesday, a spokesman told Reuters.
"There was an incident on Sunday but the vessel is now fully under control of the company and, most importantly, all the crew are safe," the spokesman said, without giving details of what occurred during the period of lost contact.
Two security sources said gunmen boarded the vessel while it was anchored near Lagos port, in the latest case of piracy off the coast of Africa's top oil exporter.
Tankers seized off the coast are often released after the oil, gasoline or other fuel on board is transferred to smaller vessels. Sometimes crew are kidnapped for ransom.
Pirate attacks off West Africa's mineral-rich Gulf of Guinea have almost doubled from last year and threaten to jeopardise the shipping of commodities from the region. They have already jacked up insurance costs.
The SP Atlanta was attacked by gunmen last year off the coast of Port Harcourt but guards on board were able to prevent the pirates boarding, security sources say.