The Turkish-owned, Maltese-flagged tanker has been hijacked by pirates off the coast of Port-Gentil, Gabon, said the Times of Malta.com.
The 2007-built MV Cotton, had a crew of 20, all of them Indian. The hijacking is believed to have happened Sunday.
"The owners of the MV Cotton lost contact with the tanker late on Sunday," said the official, who wished to remain anonymous.
"We believe it was captured by pirates in the region where such acts are common," the news site said.
The tanker was awaiting berthing in the Gulf of Guinea at the time of the hijack.
Details of the whether a ransom has been demanded are unknown.
The Turkish ambassador in Gabon has contacted authorities in the west African nation about the incident.