Pirates seized a tanker flying the Maltese flag but owned by a Turkish company off the coast of Port-Gentil, Gabon, officials said Monday.
The ship, the MV Cotton, had a crew of 20, all of them Indian.
A Turkish foreign ministry official contacted by AFP confirmed the incident, which happened late 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 Turkish ambassador in Gabon has contacted the west African country's foreign minister about the incident, the source said.