One man in his mid-twenties said he was tied with his hands behind his back and had "five layers" of other detainees above him in a truck.
"It was very hot and I was suffering a lot. I was shocked after I learned that 78 people died," said the man, declining to be identified.
"Can you imagine being laid down on the floor and there are a lot of people on top of you? You can't even move. You can't even do anything," another man said, weeping. He also did not want to be named, but described himself as a businessman.
Death by suffocation
Another detainee criticised the way authorities dispersed the demonstration and transported the Muslims, who were fasting during the holy month of Ramadan.
"I am lucky to be able to breathe today. Think about it: I'm a small person and there were four to five people piled on me," said the man.
The three men, interviewed in Narathiwat province, were among more than 1100 Muslims which the military said it had freed on Saturday from six different sites after holding them since a clash with demonstrators in Tak Bai, Narathiwat, last Monday.
Another 78 detainees died in trucks on their way to the detention facilities, officials in the majority-Buddhist kingdom said.
Another seven died as a result of wounds received at the demonstration, which security forces broke up by firing live rounds, tear gas and water cannon.
PM under pressure
Thai Prime Minister Thaksin Shinawatra, under pressure from close ally the United States, regional neighbours and the UN rights body, said on Friday he would set up an independent commission to "investigate the incident with the aim of bringing wrongdoers to justice".
But Thaksin, speaking on nationwide television, did not single out anyone for blame despite rumours that the army general who ordered soldiers to quell the protest would be sacked.
The Bangkok Post newspaper, citing security sources, said on Saturday Lieutenant General Pisarn Wattanawongkeeree's removal was only a matter of time.
Thaksin has yet to apportion
blame for the detainee deaths
"We cannot deny local security forces mishandled the case leading to the deaths of so many protesters. Some kind of action has to be taken to show our remorse for the tragedy," an unnamed security officer was quoted as saying.
The newspaper also quoted deputy army commander General Theptut Promopagorn as saying: "The army's image and credibility have been badly tarnished worldwide with this incident."
In his speech on Friday, Thaksin defended the break-up of the protest, saying efforts to end it peacefully had failed and the crowd was becoming violent.
No fresh violence
The Thai leader said he regretted the deaths and denied his administration was mistreating Thailand's Muslim minority.
"This is a matter of maintaining law and order and has absolutely nothing to do with religion," Thaksin said on Friday.
Thai Muslim leaders have said the incident could turn the poor region, home to a separatist insurgency in the 70s and 80s, into a fertile recruiting ground for the likes of al-Qaida.
Neighbours have reacted with
dismay and anger to the deaths
There were no reports of fresh violence in the region, where three bombings have killed two people and wounded more than 30 since Thursday.
Countries in the region reacted with dismay and anger to the bloodshed.
Muslims demonstrated on Friday outside Thai embassies in Malaysia and Indonesia, chanting anti-Thai slogans and waving banners saying "Stop the genocide of Muslims by Thailand" and "Thailand: The land of bloodshed".
Monday's deaths have raised concerns among Thailand's neighbours that the situation in the Malay-speaking south, where at least 440 people have been killed since January, may spiral out of control.