Bangkok, Thailand: Scores of detainees have been tortured by Thai security forces in the country’s conflict-strewn south, rights groups said Tuesday, with beatings, suffocations and death threats among a litany of alleged abuse.

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—which is flanked by an emergency decree—rebel suspects can be detained for six weeks without charge, according to a report by rights groups to be released on Wednesday documenting widespread abuses.

The study, rare research in a dangerous zone cloaked by security forces and insurgents, found 54 cases of physical and mental torture or mistreatment between 2014-15, often at military camps.

Alleged beatings of suspects, threats at gunpoint, sensory deprivation and suffocation were all routine during detention, researchers said.

‘What we have documented is the tip of the iceberg,’ said Pornpen Khongkachonkiet, of the Cross Cultural Foundation, one of the research groups.

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 region more than a century ago, and have employed brutal tactics including indiscriminate shootings, beheadings and bombings.