The ship vanished from radar and lost radio contact about 180 nautical miles north-east of Singapore, and 360 nautical miles south-east of Ca Mau Cape in Vietnam, Luu Duc Tung, deputy director of Vietnam Maritime Rescue Coordination Centre, told DPA.
It left Singapore on Thursday and was scheduled to arrive at a port in central Vietnam on Sunday.
Weather conditions were normal, Tung said. “We are considering many possibilities, including pirates,” he said.
The Vietnamese Coast Guard has requested help from authorities in Singapore, Indonesia and Malaysia to find the vessel.