Thailand's army chief called for a probe into senior army officials suspected of helping to traffic Rohingya Muslims from Myanmar through Thailand and on to a third country.
"This problem has been going on for some time. Anyone found to be involved – especially soldiers – will be prosecuted, expelled and charged with a criminal offence," army chief Prayuth Chanocha said on Monday.
Thai media on Sunday reported that a police investigation had found senior army officers, some with ranks as high as major and colonel, were involved in smuggling Rohingyas from Myanmar into Malaysia via Thailand and that the trafficking had been going on for several years.
The United Nations estimates roughly 13,000 boat people, including many Rohingyas, fled Myanmar and neighbouring Bangladesh in 2012 – a sharp increase from 7,000 a year earlier.
Around 800,000 Rohingyas live in Myanmar but are officially stateless and regarded as illegal Bangladeshi immigrants by the Myanmar government. Hundreds have fled recent sectarian violence involving Buddhists in Myanmar's western state of Rakhine. Malaysia has offered asylum to some in the past.
General Prayuth said some army officers may have become involved in the Rohingya situation because it was "hard not to sympathize with their plight."
More than 600 Rohingyas have been detained this month in what Thai authorities described as anti-trafficking raids, and more than 1,000 are now being held, including some whose boats had come ashore, said Sihasak Phuangketkeow, permanent secretary at the foreign ministry.
Some of those detained in the raids had been in hiding for many weeks. It remains unclear if they were being held against their will or simply waiting to sneak into Malaysia.
The Thai government has said it will co-operate with international humanitarian agencies to provide assistance to migrants detained after the raids, but it says Rohingyas arrested for illegal entry will be deported.
"The Rohingya found last week were not held in captivity. They were waiting to be transferred to a third country. Our records don't show any Rohingyas rescued from trafficking," said Chalwalit Sawaengpueth, chief of the Thai police's Counter-Human-Trafficking unit.
Rights groups have frequently criticized Thailand for its handling of the Rohingya and its deportation process, which leaves many illegal immigrants subject to abuse from authorities or even other Rohingyas.
"A stateless person has no other option but to rely on these trafficking networks, and it's not just the Thai authorities – their own people are also involved," said Chris Lewa, director of the Arakan Project, which campaigns for Rohingya rights.