Myanmar authorities have yet to release four Thai crew members, citing the need to follow proper procedures.
The four men are being detained in Kawthaung, Myanmar, opposite Ranong, following a gun attack on 15 fishing boats off this southern province on Nov 30 by Myanmar patrol boats, Maj Gen Thanathip Sawangsaeng, spokesman for the Defence Ministry, said on Saturday.
Myanmar officers seized Sor Charoenchai 8 vessel and detained 31 crew members - four Thais and 27 from Myanmar.
The four Thais were initially scheduled to be released on Friday but were not returned, said the spokesman.
The Thai-Myanmar Township Border Committee (TBC) had coordinated with its Myanmar counterpart about the release and was notified that legal procedures were still ongoing.
Local Myanmar authorities said they were awaiting a letter from their superiors before the four Thais could be released, said Maj Gen Thanathip.
The release date remains uncertain, he added. Earlier, Thai officials had used diplomatic channels to protest against the attack and urged Myanmar to consider whether its response was excessive.
During the attack, one crewmember of a fishing boat jumped into the sea and died.
The Royal Thai Navy shares a photo on its Facebook page of the detained crew members including four Thais, in the red square.
The four detainees were boat skipper Sunan Mongkutthong, 68, Sompong Wiwat, 61, Thavorn Phromnimit, 64, and Wirot Saphanthong Na Nakhon, 69.