Lagos - Pirates hijacked a supply ship off Nigeria's coast, but released the vessel and its 17 crew later in the day, the International Maritime Bureau said on Tuesday.
Details of the attack on Monday were not clear, including the reason for the hijacking, whether a ransom was paid and the crew's nationalities. It was released about 11 hours after the time of the initial report.
"While underway, pirates hijacked a supply vessel and took her 17 crew as hostage," the IMB said on its website. "The hijackers released the crew and vessel at 1755 UTC. The crew and vessel are safe."
A 2009 amnesty deal for militants in Nigeria's oil-producing Niger Delta region led to a sharp decline in attacks on the oil industry, though sporadic incidents continue to occur.
There has, however, been a recent upsurge in piracy off West Africa's coast by criminal gangs stealing fuel cargo in order to sell it on the lucrative black market.
Nigeria is Africa's largest oil producer.