A Vietnamese oil tanker has gone missing en route to Vietnam from Singapore, prompting fears that pirates may be responsible.
The Sunrise-689 was carrying 5,226 tons of oil products and 18 crew members when it went missing last Thursday.
It was scheduled to reach Quang Tri province in Vietnam on Sunday.
Vietnamese authorities have asked counterparts in Malaysia, Indonesia and Singapore for help in locating the vessel.
The tanker went missing 40 minutes into its journey from Singapore, sparking a search-and-rescue operation.
Some fear that pirates might be to blame.
Colonel Ngo Ngoc Thu, vice commander and chief-of-staff of Vietnam's coastguard told BBC Vietnamese: "There is no official conclusion yet, but the possibilities of technical problems or weather are very low. Our search units are trying to verify whether pirates attacked it."
South-East Asia has witnessed a number of hijackings this year, notably in the Strait of Malacca between Malaysia, Indonesia and Singapore.
The International Maritime Bureau's Piracy Reporting Centre says between April and July at least six tankers in South-East Asian waters were hijacked for their cargoes of oil products.
Recently, global efforts have focused on eradicating piracy in Somalia, allowing attacks to mount up in South-East Asian waters, home to a third of global trade flows.