V.Lucky with five Thai crewmen was carrying 170,000 liters of diesel and pumping the oil to a Vietnamese fishing boat that had three people on board and a fake license plate.
It was caught at 9:30 p.m. on November 22 in waters bordering Vietnam and Indonesia.
Coast Guard personnel also found and seized a Thompson submachine gun and 17 bullets, and said this was the first time they caught a ship with weapons in the area.
On October 24 two vessels were escorted to Phu Quoc Island for further investigation.
According to the Coast Guard, oil smuggling has been rife in southwestern waters this year.
Vietnamese coast guard personnel inspect the Thai ship they caught smuggling diesel on November 22
