Human Rights Watch spokesperson Phil Robertson said: ''We are concerned that Thailand will quickly move to deport these groups without consideration for their rights.''
Unprecedented raids by Thai authorities on two large secret camps close to the border with Malaysia have ''rescued'' about 700 Rohingya, with many women and children among them.
But the whereabouts of the group freed yesterday from a hillside camp and the second group released in a raid on a warehouse in Songkhla province today are not known.
After yesterday's raid, the first group of between 367 and 397 were housed at Songkhla Immigration and police stations around the township of Padang Bezar.
A witness in the town said the seven accused people traffickers, 11 Rohingya women and most of the 62 Rohingya children were being held at Immigration.
One of the Rohingya told the witness, an outsider who happened to be in Padang Bezar, that he had spent two months in captivity at the camp after a 20-day boat trip from Burma.
He said he had been beaten regularly because he could not raise the 50,000 to 60,000 baht to cover the cost of his illegal transfer to Malaysia.
He also told the witness that five men had disappeared during his time at the camp, and it was feared they had been put to death.
The freed Rohingya had only the clothes they wore, the witness said. ''They are smelly and there are signs of skin disease, including scabies,'' the witness said.
It was not possible to discover today what Thai authorites plan for the group of Rohingya freed yesterday or the second group of 307 freed in a raid early today.
Two-hundred and thirty men, 30 women and 47 children were freed in today's raid on a warehouse at Sadao, which is also in Songkhla province, on the border with Malaysia.
The large number of freed Rohingya is likely to further stress the illegal immigration system. Thailand's military have been ''helping on'' Rohingya boatpeople by making sure they keep heading towards ''a third country'' and do not land in Thailand.
The presence of women and children among the Rohingya boats was revealed for the first time when a vessel ran out of fuel and was apprehended off the Thai holiday island of Phuket on January 1.
The discovery may have changed attitudes in Thailand towards the surreptitious processing of the Rohingya.
With more women and children found over the past two days in the hands of people smugglers on the Thai-Malaysia border, anxiety is likely to increase.
Accusations that the Thai military sometimes sells Rohingya to people traffickers have been made to Phuketwan. The claims are impossible to prove or disprove because the present system is covert and non-transparent.
Human Rights Watch wants the Thai Government to involve the United Nations High Commissioner for Refugees to assess the welfare and rights of the freed Rohingya.
''This is what Malaysia is already doing,'' Mr Robertson said. ''We are very concerned to make sure the rights of these groups are respected.''
Between one and two Rohingya boats a day are now departing from Bangladesh or Burma with the total for the ''sailing season'' between October and April expected to exceed 20,000 people.
Now that their homes in troubled Rakhine province have been destroyed, Rohingya have told Phuketwan that they would rather make the perilous boat journey than ''die in displaced persons' camps.''
Although boatloads of Rohingya apprehended in Burma are returned to Rakhine state, Phuketwan has been told that those apprehended in Thailand are most usually transferred onto other boats, some of them provided by smugglers, to repeat the journey.
Three sources have confirmed that the 73 men, women and children apprehended off Phuket recently were placed on another boat and sent south once more.
Phuketwan contacted a media liaison officer at Thailand's Ministry of Foreign Affairs today but there was no promised return call.