The victims were among the 2,000 or more protestors who clashed with security forces outside a police station in Narahiwat province on Monday, demanding unconditional release of six suspected jailed Muslim militants.
Police brought the riot under control by using water cannon and tear gas, then fired into the air to try to scatter the crowd. Later police and soldiers shoved 1,300 bare-chested young men into trucks that took them away.
The detainees spent more than six hours in the vehicles before arriving at an army camp in a neighbouring province. Thaksin told the Thai Senate that there had been some mistakes and the authorities did not have enough trucks to transport the rioters who were arrested.
He claimed that the authorities had to pile the detainees up on top of each other, resulting in their deaths from suffocation and being crushed. Thaksin apologised for their untimely death and noted that the military had used the "soft approach" and not fired a single round into the crowd. He said rounds had been fired only in the air.
"Protestors died because they were in a weak physical condition resulting from fasting. They just collapsed in the crowded situation and anti-riot forces did not touch them," Shinawatra was quoted by the daily as saying.
He added that a large number of weapons, including M16 and AK 7
"Autopsies performed on the victims found no bullet wounds on their bodies, just bruises and small cuts on their faces," the daily Nation quoted Pornthip Rojanasunand, deputy director of the Justice Ministry's Forensic department, as saying.
Outraged Muslim leaders warned the deaths could worsen sectarian violence in the Muslim-dominated south of predominatly Buddhist Thailand.
'The situation in Muslim majority southern Thailand could turn into a bloodbath after the government's tough suppression of protestors there and the resulting death of at least 78 people by suffocation,' said the Bangkok Post, quoting leading security officials and southern Muslim leaders.
"I was totally shocked. The number of people who were reportedly killed initially was only five or six. Now it is 78. This is totally insane. Certainly this will escalate further and who knows what will happen next," the daily quoted Abdullahman Abdulsomat, Chairman of the provincial Islamic Committee in southern Thailand's Narathiwat province.
Amnesty International called on the Thai Government to impartially probe the deaths and the US government said it was "concerned about the continued loss of life."
"Thai authorities are responsible for the humane treatment of prisoners and we urge that their current investigations fully examine the circumstances of these deaths," said State Department spokesman Edgar Vasquez.
