Defence Minister Phumtham Wechayachai on Sunday demanded that Myanmar return four Thais arrested by a warship immediately, the Defence Ministry spokesman said.
Maj Gen Thanathip Sawangsaeng, spokesman for the ministry, said Phumtham ordered the Thai-Myanmar Border Coordination Centre (TBC) and the Thai-Myanmar Town Border Committee to coordinate with Myanmar authorities to return the four Thais by Sunday.
The four Thais were among 31 crew members of a fishing boat captured by a Myanmar warship early on Saturday.
Thanathip said Phumtham did not mind Myanmar authorities detaining 27 Myanmar crew members for further questioning but they must also return the captured fishing boat after due legal process.
Crew members claimed that three boats were fishing in Thai territorial waters about 20 kilometres west of Koh Phayam when they were approached by Myanmar naval boats.
They said a warship opened fire at the fishing boats. Two crew members were injured and one Thai drowned after he jumped overboard to try to avoid arrest.
Thanathip said the TBC would conduct a fact-finding probe into exactly where the boats were fishing when they were attacked by Myanmar naval boats.
He said the TBC has also sent a formal protest to the Myanmar naval base at Koh Song.