Pirates boarded a fully loaded supertanker off the coast of Nigeria on Tuesday, kidnapping 19 crew members.
The kidnapped crew are still missing, a spokeswoman for Navios, the ship’s owner, said on Wednesday.
Crew members who avoided being kidnapped were able to sail the vessel to a safe location, the spokeswoman said.
She said the company’s priority was the safe return of those who were missing.
The Nave Constellation, can carry 2 million barrels of oil. There was no damage to the ship when the pirates boarded.
The incident occurred about 77 nautical miles from Bonny Island, a key loading point for Nigerian crude. The vessel had only recently collected its cargo.
The incident will be of concern to insurers considering the risks of collecting oil from Africa’s biggest producer.
The Gulf of Guinea has been the site of sporadic incidents of piracy for a few years but an attack on a supertanker is rare.
Nigeria suffered a spate of militancy that crippled its oil industry in 2016, but it rarely strayed into shipping.
Out of 95 attacks worldwide where hijackers boarded the vessel in the first nine months of 2019, 17 took place in Nigerian waters, data from the International Maritime Bureau shows.
As a region, the Gulf of Guinea accounts for almost 82 per cent of crew kidnappings globally.