Thai security forces have tortured scores of detainees in the country's conflict-strewn south, rights groups said Tuesday, with beatings, suffocations and death threats among a litany of alleged abuses.
Special security laws govern Thailand's Muslim-majority southernmost provinces, where more than 6,500 people, mostly civilians, have been killed in a 12-year insurgency against Thai rule.
Under martial law and the emergency decree that smothers the south, suspected rebels can be detained for six weeks without charge.
As a result many young Muslim men have been swept into arbitrary detention where they are vulnerable to torture, according to a report by several well-respected advocacy groups to be released on Wednesday.
The study, rare research in a dangerous zone cloaked by security forces and insurgents, is based on interviews with 54 former detainees between 2014-15 who alleged they were physically or mentally tortured over the last few years.
Alleged beatings of suspects, threats at gunpoint, sensory deprivation and suffocation were all routine during detention, researchers said.
Many of the suspects were later released without charge.
"What we have documented is the tip of the iceberg," said Pornpen Khongkachonkiet, of the Cross Cultural Foundation, a rights group.
The situation has worsened since Thailand's 2014 coup put the military in power, she added.
"With no accountability or oversight mechanisms since the coup... interrogation officers have almost a free hand" over detainees, she explained.
The insurgents are seeking greater autonomy from Thailand, which annexed the culturally distinct region more than a century ago.
The rebels employ brutal tactics including shootings, beheadings and bombings often targeting perceived civilian collaborators such as teachers and even Buddhist monks.
- 'I couldn't breathe' -
One suspect, Weasohok Doloh, told AFP that he was hauled into custody in May 2015 on suspicion of involvement in a bombing -- an accusation he denies.
He was taken to Inkayuth military camp, an interrogation centre in Pattani province, where he alleged he was abused over several days.
"At first they just slapped me," the 32-year-old builder said, adding he resisted confessing to links with the rebels.
But the abuse worsened and after a few days he alleged he was stripped naked by three interrogators who also tied his hands.
"Suddenly one (interrogator) pushed me onto a chair and forced a plastic bag over my head. I couldn't breathe... they released the bag when I said I would confess. But I had nothing to confess to, so they did it again," he said.
In total he spent 84 days in custody before prosecutors decided not to press charges.
"Inkayuth military camp is a place where bad things are swept under the carpet," says Anchana Heemmina of Duay Jai, a local rights group which co-authored the report.
"We have heard stories of suffering from there for 12 years," she added, urging the army to allow lawyers access to suspects from the moment of arrest.
A Muslim man died in custody at Inkayuth in December last year. The army says it was from a heart attack.
A separate report released last week by the Muslim Attorney's Centre (MAC), a southern-based advocacy group, collected testimony of 75 people who alleged they were the tortured in custody in 2015.
Army spokesman Pramote Prom-In, dismissed the torture allegations contained in both reports as "imaginary".
"Losing their freedom may be torture for them... but we need to enforce the law," he told AFP.
"Detainees are allowed family visits and arrests are made in front of witnesses," he added.
The military has hailed a record drop in violence in recent months as the result of better intelligence-led operations since it took power.
It is also engaged in contacts with a number of rebel representatives that Bangkok hopes will lead to full peace talks.
But critics cast doubt on the army's sincerity and the ability of their rebel interlocuters to tug the leash of the rebel foot soldiers.