Pirates who boarded and robbed a Thai oil tanker in Malaysian waters made off with 2,000 tonnes of bunker oil and five tonnes of diesel oil before laying a bomb on the vessel.
Theekhathat Charoensuk, the captain of the Thai tanker Lapin, sought help from another ship after navigating the tanker into Thai waters yesterday.
His boat, which was transporting a large quantity of oil from Singapore, was robbed in the Strait of Malacca on Friday around 8pm.
Navy and marine police were contacted to help the ill-fated vessel, after its communication system started malfunctioning.
According to authorities, Mr Theekhathat said six to eight pirates, believed to be Indonesian, stopped the Lapin and forced the crew to surrender. Three of the pirates were armed with guns, while the others carried swords.
The pirates brought a larger boat alongside the tanker and siphoned off 2,000 tonnes of bunker oil and five tonnes of diesel oil.
Before leaving with the stolen oil supplies, the pirates placed a device — which appeared to be a homemade bomb — on the tanker's flying bridge area.
According to the captain, the device looked like a TNT explosive and was held together by electrical wire.
The captain brought the tanker into Thai waters and anchored it between Tarutao and Lipe islands off Satun province while he contacted marine police for assistance.
Rear Admiral Somchai Na Bangchang, the Third Naval Area Command's chief of staff, said all 15 crew members were unharmed but a bomb remained on board.
The navy instructed the vessel to anchor roughly 11km from Pak Bara deep-sea port in Satun, and sent its explosive ordnance disposal team to inspect the bomb.