KABUL — A gruesome video that appears to show Afghan security forces torturing a detainee emerged on social media Wednesday, prompting the country's chief executive to vow the perpetrators would be punished. It is unclear whether the detainee, who reports said was a suspected suicide bomber, survived the abuse.

The amateur footage was reportedly taken in the Panjwai district of southern Kandahar province, and it shows men in Afghan police uniforms tying another man to the back of a truck and dragging him across the pavement. After he is untied, one of the men in uniform bites hard on the detainees' arm, forcing him to the ground. The prisoner is then hustled into the cab of the truck, clearly marked "police," before the video ends.

The video is undated, and the Interior Ministry has said that the perpetrators have not been identified. In a statement Wednesday, the ministry said the Kandahar police force has been ordered to investigate.

Afghan security forces have "clear orders on how to behave with prisoners," Afghan Chief Executive Abdullah Abdullah posted on Twitter on Wednesday. The Interior Ministry "will investigate this incident and those involved will end up punished," he said.

Torture is banned by Afghan law but is rife in detention facilities across the country, according to the United Nations Mission in Afghanistan. A U.N. report last year said authorities have not been held accountable for abuses, which range from electric shocks and near-asphyxiation to beatings with pipes and cables.

"Many Afghan security and police officials interviewed appeared not to accept that torture is illegal and saw it as a proper tool to obtain valuable intelligence information," the U.N. report said.

The United States has spent more than $60 billion on training and equipping Afghan police and the army.

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