More likely a regular auxiliary unit of Myanmar Navy, but not yet listed.

Looks like her here (or a sister), on naval duty with "557" in May 2015:
http://www.thesundaily.my/news/1436773

@WadeArmstrong: At the time of this photo, the tug was on its way to do a tow job for the Myanmar Navy

The " convoy board" name plate is black and is attached to the railings ON TOP of the wheelhouse

Not listed in Jane's Fighting Ships, but it is flying the Myanmar Naval Ensign and foredeck crew have the same ensign on their shoulders. Most probably operates in support of the Myanmar Port Authority but operated by the Navy.