Pirates have hijacked a Greek-owned oil tanker carrying 135,000 metric tonnes of crude oil while in the Arabian Sea, the first successful attack on an oil tanker off the Horn of Africa in more than a year.
Dynacom Tankers Management, which manages the vessel, said it had lost contact with the crew of the MT Smyrni, a Suezmax-class tanker, following the attack off Oman at 1115 GMT on Thursday.
"The Liberian-flagged Tanker, the MT Smyrni, is carrying a cargo of 135,000 MT of crude oil," it said.
Suezmax tankers typically can transport a crude oil cargo of up to one million barrels, compared with two to three million barrels for very large oil tankers.
Dynacom gave no further details but a Kenya-based piracy expert, Andrew Mwangura, said the vessel was headed for the Somali coastline.
Industry websites said the vessel had sailed from Turkey, but there were mixed reports about its destination.
"Aboard are nine Indians and about eight Filipinos," Mwangura, who is maritime editor of Somalia Report, a private regional news portal, said.
"It is headed to Somalia."
OceanUSlive.Org, a social-networking website for the maritime industry, said the attack was one of four to have taken place in the Arabian Sea in the past few days after a lull in pirate activity.
International criminal enterprise
The hijack success rate for Somali pirates has dropped sharply in recent months, due in part to more merchant ships turning to armed security guards, razor wire and water cannons to protect themselves.
In its statement, Dynacom did not disclose whether the Smyrni was carrying private security personnel.
A pirate gang fired rocket-propelled grenades on Wednesday at a crude tanker 56km east of Socotra, an island lying between Yemen and Somalia's lawless coastline, OceanUSlive.org said.
Seaborne gangs have raked in an estimated $150m in ransoms in what has become a highly organised, international criminal enterprise, security analysts say.
Somali pirates in December released an Italian-owned Aframax oil tanker, smaller than the Suezmax, after receiving an $11.5m payment. The Savina Caylyn was seized in February, 2011.
Despite successful efforts to quell attacks in the Gulf of Aden, international navies have struggled to contain piracy in the Indian Ocean and Arabian Sea owing to the vast distances.