Myanmar's navy has briefly detained journalists who tried to reach a remote island where more than 700 migrants were being held after their ship was found drifting off the country's southwestern coast.

Some were forced to hand over camera memory cards or to sign documents Sunday saying they would not try to make the journey again.

The boat that was brought to Thameehla Island late last week was one of more than a half-dozen that have either washed to Southeast Asian shores or been rescued following a crackdown on human trafficking networks.

Around half the 3,700 people have been Rohingya Muslims fleeing persecution in Myanmar and the remainder Bangladeshi's escaping poverty.

Myanmar insisted Sunday all 727 on board the ship tied to a navy vessel off Thameehla Island were Bangladeshi.