A French-owned oil tanker that was reported missing Sunday off the Ivory Coast and is believed to have been hijacked by pirates, an official with the International Maritime Bureau (IMB) said Monday.

The owners of the Luxembourg-flagged tanker carrying 17 crew members reported the vessel missing after losing contact with it. The last known location of the vessel was 70 nautical miles south of the port city of Abidjan.

The ship is believed to have been hijacked by pirates that have been operating in the Gulf of Guinea, said Noel Choong, head of the Bureau's Kuala Lumpur-based piracy reporting center, the Associated Press reported. Choong has not divulged other details about the ship or its owners.

The suspected hijacking is the latest in a series of such attacks by the pirates in the region, which has witnessed an escalation in maritime crimes targeting the naval vessels in recent years. The Gulf of Guinea is considered one of the world’s piracy hot spots, along with the Gulf of Aden between Somalia and the Arabian Peninsula, and the waters between Indonesia and Singapore.

"It appears pirates are moving towards the Ivory Coast because Nigeria and Benin have increased patrols in the Gulf of Guinea," said Choong, who declined to elaborate further on the incident.

A United Arab Emirates-owned chemical tanker anchored off the Nigerian port city of Lagos was attacked by the pirates Monday. A sailor who was shot by the pirates was shifted to hospital where he is said to be recovering.

On Thursday, pirates had attacked another tanker off Nigeria with rocket-propelled grenades and machine guns, the Maritime Bureau said. The ship and the crew escaped the attack but the hull of the vessel was damaged by weapons fire.

The IMB reports that five attacks were reported in the region in 2012, up from one in 2011, while 58 attacks, including hijacking, murder and other violence were reported in the Gulf of Guinea in 2012.

“Piracy is rising in the Gulf of Guinea, with 58 incidents recorded in 2012, including 10 hijackings and 207 crew members taken hostage. Pirates in this area are particularly violent, with guns reported in at least 37 of the attacks. Benin is an exception, showing a sharp fall from 20 incidents (including eight hijackings) in 2011 to two (including one hijacking) in 2012,” the International Maritime Bureau said in a statement.

The agency had pointed out that hijack incidents in waters off the east African nation of Somalia have been halved in 2012, owing primarily to increased naval patrols by India, France and the United States.

“The continued presence of the navies is vital to ensuring that Somali piracy remains low,” said Captain Mukundan, director of the IMB. “This progress could easily be reversed if naval vessels were withdrawn from the area.”

The international piracy watchdog had issued a warning to ships plying the Gulf of Guinea to be on vigil for pirates. The region includes waters off Nigeria, Cameroon, Benin, Ghana, Togo and the Ivory Coast.

Unlike the Somalia pirates who hold crews and the ships for ransom, Nigerian pirates tend to attack fuel cargo to steal and sell their loot in the booming black market.