The Thai military is accused of sending refugees off to likely death
Thailand's new Prime Minister Abhisit Vejjajiva has met human rights officials to discuss claims of Thai army abuse of asylum seekers.
His staff say they are investigating reports that troops sent Rohingya people from western Burma back to sea in boats without engines.
Reports of more than 500 deaths have poured in over the weekend, from Indian officials and regional newspapers.
These suggest that more than 1,000 Rohingya were put to sea in December.
"The prime minister told the [National Human Rights] Commission not to worry about the Rohingya case," deputy government spokesman Buddhipongse Punnakanta told reporters.
"He assigned all the government authorities involved to keep him up-to-date," he said.
Deputy Prime Minister Suthep Thaugsuban said he had been informed that the soldiers did not abuse the Rohingya.
"I myself believe the officers did not do such a thing because Thai people have generosity and kindness," he said.
Indian officials told reporters that they had rescued hundreds of Rohingya refugees, who are mostly Muslim and live along the border of Burma and Bangladesh.
"They said they were taken to an island off the Thai coast and beaten up before being forced into boats and pushed into the high seas," said Ranjit Narayan, a police official on India's remote Andaman and Nicobar islands.
Coast guard commander SP Sharma told AFP news agency that India had rescued 446 refugees from four boats since the end of December.
The figures are in line with those of the Sunday Morning Post, a Hong Kong newspaper, which said it had compiled a toll of 538 missing or dead.
According to Mr Sharma, the migrants said they had been arrested by Thai officials and set adrift without engines or navigational equipment.
"Some survivors also said their boat was towed out to sea by the Thai navy and given two sacks of boiled rice and two gallons of water before being abandoned in the middle of the sea," he said.
One traumatised survivor the BBC spoke to said captured migrants were towed out to sea and forced onto an unpowered boat at gunpoint. He said four men who resisted were thrown overboard with their hands and feet tied.
The remaining captives were then left to drift for days with only very little food and water.
Privately, some Thai military and police sources have admitted to the BBC that migrants had been sent back to sea.
They say the rising numbers of Rohingyas reaching Thailand from Burma or Bangladesh are seen as a security risk, because of fears they may include Islamic militants.
But senior military figures have denied the accusations.
The South China Morning Post quoted Thai army chief Anupong Paojinda as denying that any Rohingya refugee had "been tortured".
But the paper said he did not specifically address the claims that refugees had been deliberately set adrift.
"Authorities followed the regular process when arresting the illegal migrants," Thai navy spokesman Captain Prachachart Sirisawat told AFP.
The United Nation's refugee agency UNHCR - whose Asia headquarters is based in the Thai capital - has expressed serious concern about the reports.
UNHCR's Kitty McKinsey said that if the allegations turned out to be true, Thailand would be "putting people's lives at risk by towing them out to sea", breaching human-rights conventions.
The Rohingya are stateless and face persecution from Burma's military regime.