The International Maritime Bureau (IMB) said in an online incident report that “an offshore tug was attacked and boarded by pirates” on Sunday around 55 nautical miles off Brass.
The IMB said it was awaiting further details on the 17 February incident.
Maritime risk outfit AKE told Reuters there were unconfirmed reports that the vessel involved was one of Bumi Armada’s Armada Tuah fleet of anchor-handling tug supply vessels.
AKE said the reports suggested an unknown number of foreigners had been kidnapped.
The Nigerian navy did not respond to requests for comment to the wire service.
Bumi Armada did not immediately respond to a request for comment from Upstream.
AKE commented meanwhile that “if confirmed, the attack would be the third offshore kidnapping in the area in 10 days, following the attacks on Esther C and Walvis 7”.
Piracy off the Nigerian coast and elsewhere in the Gulf of Guinea is on the rise, with at least five attacks in the waters off Africa’s most populous nation this month.
The coastline, rich in natural resources such as cocoa and metals, is second only to the waters off Somalia for the risk of pirate attacks, which drives up shipping and oil industry costs on the busy oil route.