By Joe Bavier
ABIDJAN (Reuters) - A French-owned Luxembourg-flagged tanker with 17 crew members that went missing off Ivory Coast at the weekend is believed to have been hijacked by Nigerian pirates, the International Maritime Bureau said on Monday.
The IMB, a division of the International Chamber Of Commerce charged with fighting maritime crime, issued a security alert for West Africa's Gulf of Guinea following a spate of violent attacks on vessels in recent days.
The Gulf of Guinea is second only to the waters around Somalia for piracy. The hijacking, if confirmed, would be the second vessel seizure off Ivory Coast in less than three weeks.
"The owner lost contact on (February) 3rd. We believe it was hijacked with 17 crew on board," said Noel Choong, head of the IMB's piracy reports division based in Malaysia.
"The situation in the Gulf of Guinea is quite bad right now. There have been three attacks there in the past five days," he said, adding that the other incidents had occurred off the coast of Nigeria.
Luxembourg's government said in a statement released on Monday that the vessel, named the Gascogne, is owned by French company SEA-Tankers.
Neither authorities in Luxembourg nor the IMB released the nationalities of the ship's crew members, but France's foreign ministry said none were French.
Port officials in Ivory Coast's commercial capital Abidjan said they were still investigating the circumstances surrounding the Gascogne's disappearance, but said the ship was not scheduled to dock in the country.
Many of the pirate gangs in the Gulf of Guinea are offshoots of militant groups that once operated in Nigeria's oil-rich Niger Delta, and attacks in the waters off Nigeria, Togo and Benin have been commonplace for years.
Ivory Coast recorded its first vessel hijacking last October when suspected Nigerian pirates seized a Bahamas-flagged tanker carrying more than 32,000 metric tons of gasoline near Abidjan's port. The 24 crew were later freed unharmed.
Gunmen attempted, but failed, to seize a ship anchored off Abidjan's port in December, and last month pirates took control of a tanker carrying 5,000 metric tons of fuel as it waited to unload its cargo at Abidjan's tanker terminal.
"It appears that the Nigerian pirates are spreading. All of these vessels were tankers carrying gas oil. They're all taken back to Nigeria to siphon off the oil, then the crews are freed," Choong said.
"This whole process takes about five or six days," he said.
(Additional reporting by Robert-Jan Bartunek in Brussels; Editing by Daniel Flynn and Jon Hemming)