The Malaysian Maritime Enforcement Agency (MMEA) spotted and intercepted the two boats about 70 nautical miles off the fishing village of Kuala Kemaman in Malaysia's Terengganu State Saturday morning, the Bernama reported.
The crew of 13 fishermen, aged between 14 and 54, failed to show valid travel documents or permits to fish in Malaysian waters, the report said.
"All of them did not exhibit valid work permits from the Immigration Department," Bernama reported, quoting Maritime Commander Rashidilhadi Abd Rashid, director of Kemaman Maritime Zone.
The MMEA also seized a total of 40 kilograms (88 pounds) of squid and fishing equipment worth RM600,000 ($147,208) from the vessels.
The case is being investigated under the Fisheries Act 1985 which levies a fine of not exceeding RM1 million for the skipper and not exceeding RM100,000 for each crew member or a jail term not exceeding two years, upon conviction on the offense of harmful alteration of fish habitat.
Many Vietnamese fishermen have recently been charged with fishing violations in neighboring countries’ waters.
To prevent illegal fishing, Vietnam’s Fisheries Resources Surveillance Department has been trying to raise awareness about maritime boundaries and international maritime laws, and conducting frequent patrols to prevent potential violations.