Eight men believed to be pirates fleeing from the hijacked Malaysian-flagged tanker Orkim Harmony were arrested near Tho Chu Island in the Mekong province of Kien Giang on Friday.
Colonel Doan Bao Quyet, political commissar of the Maritime Police Zone 4, said the eight were being held by the Vietnamese maritime police force at the Maritime Police Zone 4 High Command on Phu Quoc Island for further investigation.
The Malaysian tanker was found in the Gulf of Thailand on Friday.
The tanker, which was carrying about 6,000 tonnes of petrol worth an estimated 21 million ringgit (US$5.6 million), went missing on June 11 en route from Malaysia's western coast to the port of Kuantan on the east.
From around 6pm on Thursday, Malaysian authorities kept the Vietnamese Maritime Police updated about the location of the ship, which was close to Vietnamese waters south-west of Tho Chu Island.
They also sent a naval ship to the spot. The Malaysian forces negotiated by radio with the hijackers.
The Vietnamese Maritime Police sent vessels CSB 2002 and CSB 2004 to help with the search.
Two Malaysian aircraft and a P3C Orion of the Royal Australian Air Force were also dispatched to track down the vessel.
At 8am on Friday, the Vietnamese were informed that the pirates had left the tanker using one of its lifeboats.
At 9.30am, the Maritime Police was informed by its Tho Chu Island unit that a lifeboat with eight foreigners claiming their fishing vessel had sunk at sea had landed on the island.
The Maritime Police believed it was the lifeboat from the hijacked tanker.
It then sent sailors and translators from CSB 2002 and CSB 2004 to Tho Chu Island to interrogate the suspects.
It said later that the pirates had held the captain of the tanker captive and injured 11 sailors. They also stole the crew's possessions before leaving the tanker.
According to Major General Nguyen Quang Dam, Commander of the Maritime Police, the search for the hijacked Orkim Harmony was very difficult because it had been repainted and had all its equipment switched off.
The joint effort by the Vietnamese, Malaysians, and international organisations had exerted pressure on the hijackers, forcing them to flee from the hijacked tanker, Tuoi Tre (Youth) newspaper quoted him as saying.
VNS