Yangon (AFP) - Myanmar authorities must investigate a video showing men in military uniforms viciously beating and threatening to kill handcuffed detainees suspected of being ethnic rebel fighters, rights groups said Sunday.
The video came as negotiators from the civilian-led government of Aung San Suu Kyi and the military held peace talks with more than a dozen ethnic rebel groups in the capital, aimed at ending some of the world's longest running civil wars.
The unverified footage first surfaced on Facebook on Saturday morning and quickly went viral.
It showed several men dressed in army uniform kicking three handcuffed men in civilian clothes, part of a wider group of people detained outside some rural houses.
At one point in the 17-minute long video, a uniformed man smashes his helmet into the face of one of the victims.
The men in army fatigues can be heard asking the handcuffed detainees whether they belong to the Ta'ang National Liberation Army (TNLA), an ethnic rebel group from north-eastern Shan State currently fighting the military.
Rights groups called on Myanmar's government to investigate whether troops were responsible.
"We're gravely concerned about the men who were savagely beaten in this video," said Matthew Smith from Fortify Rights. "The Myanmar authorities should take urgent action to protect the lives of these men."
Human Rights Watch and Amnesty International also called for an investigation.
Fortify Rights said the uniforms identified the soldiers as being from the Light Infantry Division 88, a unit know to be fighting the TNLA in Shan.
- 'I will break your teeth' -
Throughout the clip soldiers threaten to kill the detainees.
"Even though you don't have a gun, you are still part of the resistance," one officer is heard saying. "If you say you don't have anything, I'm going to break all your teeth."
Others threaten to cut the detainees' throats with a machete and order them to speak in Burmese, not their mother tongue.
Myanmar's border regions have burned for decades with insurgencies led by ethnic minority armed groups fighting for greater autonomy.
Suu Kyi has made signing a nationwide peace deal a priority of her government but the peace process has had limited success.
Under Myanmar's junta-era constitution Suu Kyi has little control over the military and fighting is currently at its most ferocious in years.
Distrust of Myanmar's notoriously abusive military runs deep, especially among ethnic rebel groups.
The Nobel laureate has repeatedly defended the army's operations in western Rakhine state where tens of thousands of Muslim minority Rohingya have fled a recent military crackdown.
The UN says authorities may have committed crimes against humanity and ethnic cleansing in the crackdown but Suu Kyi has rejected calls for an independent fact finding commission.
Last week Myanmar's military said its own probe had found no evidence of atrocities committed by its troops in Rakhine -- although it said one soldier was punished for stealing a bike.