NARATHIWAT: A Vietnamese fishing trawler was seized and four crewmen arrested late on Monday for fishing illegally in Thai waters in Muang district off this southern province.

A Royal Thai Navy patrol vessel spotted seven Vietnamese vessels fishing in Thai waters about 37 nautical miles from Laem Tachi cape, west of Pattani province, and about 26 nautical miles from the mouth of the Bang Nara River, north of Narathiwat province, around 9pm on Monday, Capt Thattham Na Songkhla, deputy director of the Thai maritime enforcement command centre in Narathiwat, told reporters on Tuesday.

They attempted the flee and the patrol boat gave chase and fired warning shots. They did not stop.

A second warning burst was fired, but the trawlers only increased speed, Capt Thattham said.

The patrol boat kept chasing the rearmost vessel. Around 11.30pm, smoke was seen coming from the vessel's engine room and it stopped. All four crewmen jumped into the sea. 

The crew were rescued and taken to Narathiwat pier in Muang district for interrogation on Tuesday morning. The trawler was seized.

They were then taken to Muang district police and faced charges of colluding to fish for commercial purposes without permission, fishing illegally in Thai waters, and entering the country illegally.

Health officials checked the crew's temperatures and took samples for Covid-19 screening.  Their temperaturs were normal.

The four Vietnamese crewmen wait for body temperature checks. (Photo supplied/Waedao Harai)