The exact numbers are not known, but the UN High Commissioner for Refugees says it triangulated reports in the media and other sources and estimates the current number could be over 3,000 or more that no one knows about.
More than 3,000 Rohingya minority Muslims fleeing persecution in Myanmar and Bangladeshi economic migrants also on the boats with them have already landed in Indonesia and Malaysia, and over 100 in Thailand.
Only Rohingyas are being given a one-year temporary shelter while Bangladeshis face repatriation.
The US military says it is preparing to help countries in the region address the humanitarian crisis of the Rohingya migrants stranded at sea.
More From This Section
Pentagon spokesman Lt Col Jeffrey Pool told The Associated Press yesterday that the Department of Defense "is responding to this crisis and taking this seriously. We are preparing to stand up maritime aviation patrols throughout the region and working with local partners to help with this issue."
The Myanmar government says it will attend a regional meeting on the Rohingya humanitarian crisis next week.
They want to discuss the root causes of the exodus of Rohingya Muslims from Myanmar as well as Bangladeshi migrants, thousands of whom have been stranded at sea.
More than 3,000 boat people have landed in Indonesia, Malaysia and Thailand in recent weeks, and thousands more are believed to be adrift and their lives in danger.
For decades, the Rohingya have suffered from state- sanctioned discrimination in majority-Buddhist Myanmar. Denied citizenship by national law, they are effectively stateless.
In the last three years, attacks on Rohingya have left hundreds dead.