Thai soldiers are detaining illegal migrants from Bangladesh and Burma and forcing them back out to sea in boats without engines, survivors say.
Survivors say their hands were tied and they were towed out to sea with little or no food or water.
About 500 migrants are now recovering from acute dehydration in India's Andaman islands and the Indonesian province of Aceh.
Thai officials were not immediately available for comment.
But sources in the police and army confirmed to the BBC's Jonathan Head in Bangkok that asylum seekers are being pushed out to sea. They did not provide further details about the practice.
Thousands of poor Burmese and Bangladeshis try to reach south-east Asian nations in search of work.---
"Thai soldiers tied up our hands and then put us in boats without engines. These were towed into the high sea by motorised boats and left to drift," said Zaw Win, a survivor rescued by Indian coast guards off the coast of Little Andamans after drifting for 12 days.
"We were without food and water. The Thai soldiers clearly wanted us to die on the boats," Win told the BBC by telephone from a camp where survivors are being cared for.
Other survivors said that about 400 migrants were put on a huge boat by soldiers. It was equipped with only two bags of rice and two drums of drinking water.
"The food and water ran out in two days. After that we were starving for nearly 15 days before we saw a lighthouse and jumped into the sea and tried swimming ashore," Mohammed Said told the BBC.
Thailand has every right to defend its sovereignty and borders. But the military should do it in a legal and a systematic way that is humane.
The problem is only going to get worse with the international economy the way it is. Also, as long as Thailand is in a geographic position between much poorer countries run by corrupt regimes that are a hundred times worse than we get in Thailand, the workers will continue to come.
It is shameful how the Thai media continues to ignore how these people are treated. But as long as the military is doing it instead of Thaksin, it will be covered up.
Bangkok Pundit has more here.