The Malaysian Enforcement Maritime Agency's Labuan Maritime Enforcement Chief Captain Che Adnan Md Isa said investigations showed that six masked men wearing dark green overalls climbed on board the ship and tied up all the 22 crewmen before confining them in a room at about 11.30pm.
He said the men then ordered the ship captain and his chief officer to stop the ship, as a vessel approached and pulled up beside the ship, where it started to pump a total of 100 metric tons of diesel out of the ship and into the vessel.
The ship was also ransacked by the intruders who made off with valuables they found on the ship, but not before they destroyed the radar and navigation equipment on board.
"The crew which comprised 15 Malaysians, three Indonesians, two Bangladeshis, one Indian and one Filipino were not harmed in the incident and they were only allowed to sail to Labuan after ten hours of being held captive," he said.
The case, he said, is being investigated under Section 395 of the Penal Code for gang robbery, which carries up to 20 years in prison and caning.